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Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 14 Haloalkanes and Haloarenes

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Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes Textual Evaluation Solved

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes Multiple Choice Questions

Question 1.
The IUPAC name of  is ………….
(a) 2-Bromopent – 3 – ene
(b) 4-Bromopent – 2 – ene
(c) 2-Bromopent – 4 – ene
(d) 4-Bromopent – 1 – ene
Answer:
(b) 4 – Bromopent – 2 – ene

Question 2.
Of the following compounds. which has the highest boiling point’?
(a) n-Butyl chloride
(b) Isobutyl chloride
(c) t-Butyl chloride
(d) n-propyl chloride
Answer:
(a) n-Butyl chloride

Question 3.
Arrange the following compounds in increasing order of their density.
(A) CCl₄
(B) CHCl₃
(C) CH₂Cl₂
(D) CH₃Cl
(a) D<C<B<A
(b) C<B<A<D
(c) A<B<C<D
(d) C<A<B<D
Answer:
(a) D<C<B<A

Question 4.
With respect to the position of – Cl in the compound CH₃ – CH = CH – CH₂ – Cl, it is classified as ………..
(a) Vinyl
(b) Allyl
(c) Secondary
(d) Aralkyl
Answer:
(b) Allyl

Question 5.
What should be the correct IUPAC name of diethyl chioromethane?
(a) 3-Chioropentane
(b) 1-Chloropentane
(c) 1-Chloro- 1, 1, diethylmethanc
(d) 1-Chloro- 1 -ethylpropane
Answer:
(a) 3-Chioropentane

Question 6.
C-X bond is strongest in …………
(a) Chioromeihane
(b) lodomethane
(c) Bromomethane
(d) Fluoromethanc
Answer:
(d) Fluoromethane

Question 7.
In the reaction  X + N₂, X is …………

Answer:

Question 8.
Which of the following compounds will give racemic mixture on nucleophilic substitution by OH^– ion?

(a) (i)
(b) (ii) and (iii)
(c) (iii)
(d) (i) and (ii)
Answer:
(c) (iii)

Question 9.
The treatment of ethyl formate with excess of RMgX gives –

Answer:
(c) R—CHO

Question 10.
Benzene reacts with Cl₂ in the presence of FeCl₂ and in absence of sunlight to form –
(a) Chiorobenzene
(b) Benzyl chloride
(c) Benzal chloride
(d) Benzene hexachloride
Answer:
(a) Chiorobenzene

Question 11.
The name of C₂F₄Cl₂ is –
(a) Freon – 112
(b) Freon – 113
(c) Freon – 114
(d) Freon – 115
Answer:
(c) Freon – 114

Question 12.
Which of the following reagent is helpful to differentiate ethylene dichloride and ethylidene chloride?
(a) Zn / methanol
(b) KOH / ethanol
(c) Aqueous KOH
(d) ZnCl₂ / Cone. HCl
Answer:
(e) Aqueous KOH

Question 13.
Match the compounds given in Column I with suitable items given in Column II.
Answer:

Code:
(a) A→2,B→4,C→1,D→3
(b) A→3,B→2,C→4,D→1
(c) A→1,B→2,C→3,D→4
(d) A→3,B→1,C→4,D→2
Answer:
(d) A→3,B→1,C→4,D→2

Question 14.
Assertion : in monohaloarenes, electrophilic substitution occurs at oriho and para positions.
Reason : Halogen atom is a ring deactivator.
(a) If both assertion and reason arc true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If assertion is true but reason is false.
(d) If both assertion and reason are false.
Answer:
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.

Question 15.
Consider the reaction, CH₃CH₂CH₂Br + NaCN → CH₃CH₂CH₂CN + NaBr This reaction will be the fastest in …………
(a) ethanol
(b) methanol
(c) DMF (N, N’ – dimethyl forrnamide)
(d) water
Answer:
(c) DMF (N, N’ – dimethyl fonuarnide)

Question 16.
Freon-12 is manufactured from tetrachioromethane by …………
(a) Wurtz reaction
(b) Swarts reaction
(c) DMF (N, N’ – dimethyl tòrmamide)
(d) water
Answer:
(c) DMF (N, N’ – dimethyl formarnide)

Question 16.
Frcon-12 is manufactured from tetrachioromethane by …………
(a) Wurtz reaction
(b) Swans reaction
(c) Haloform reaction
(d) Gattennann reaction
Answer:
(b) Swarts reaction

Question 17.
The most easily hydrolysed molecule under S_N¹ condition is …………
(a) allyl chloride
(b) ethyl chloride
(c) isopropyl chloride
(d) benzyl chloride
Answer:
(a) benzyl chloride

Question 18.
The carbocation formed in S_N¹ reaction of alkyl halide in the slow step is …………
(a) sp³ hybridised
(b) sp² hybridised
(c) sp hybridised
(d) none of these
Answer:
(b) sp² hybridised

Question 19.
The major products obtained when chiorobenzene is nitrated with HNO₃ and cone. H₂SO₄
(a) 1-chloro-4-nitrobenzenc
(b) 1-chloro-2-n itrobenzene
(c) 1-chloro-3-n itroberizene
(d) 1-chloro- 1 -nitrobenzene
Answer:
(a) 1 -chloro-4-nitrobenzene

Question 20.
Which one of the following is most reactive towards nucleophilic substitution reaction?

Answer:

Question 21.
Ethylidene chloride on treatment with aqueous KOH gives …………
(a) acetaldehyde
(b) ehtylene glycol
(c) formaldehyde
(d) glyoxal
Answer:
(a) acetaldehyde

Question 22.
The raw material for Rasching process is …………
(a) chiorobenzene
(b) phenol
(c) benzene
(d) anisole
Answer:
(c) benzene

Question 23.
Chloroform reacts with nitric acid to produce …………
(a) nitro-toluene
(b) nitro-glycerine
(c) chloropicrin
(d) chioropicric acid
Answer:
(c) chioropicrin

Question 24
Acetone X, X is …………
(a) 2-propanol
(b) 2-methyl-2-propanol
(c) 1 -propanol
(d) acetonol
Answer:
(b) 2-methyl-2-propanol

Question 25.
Silver propionate when refluxed with Bromine in carbon tetrachioride gives …………
(a) propionic acid
(b) chioroethane
(c) bromoethane
(d) chioropropane
Answer:
(c) bromoethane

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes Short Answer Questions

Question 26.
Classify the following compounds in the form of alkyl. allylic, vinyl, benzylic halides:
(a) CH₃-CH = CH-Cl
(b) C₆H₅CH₂I

(d) CH₂ = CH – Cl
Answer:
(a) CH₃-CH = CH-Cl – Allylic halide
(b) C₆H₅CH₂ – Benzylic halide

(d) CH₂ = CHCl – Vinyl halide

Question 27.
Why chlorination of methane is not possible in dark?
Answer:

• Chlorination of methane is a free radical substitution reaction.
• Before chlorine reacts with methane, the Cl-Cl single bond must break to form free radicals and this can only be done in the presence of ultraviolet light.
• In dark, chlorine free radicals formation is not possible and so chlorination of methane is not possible in dark.
• The ultraviolet light is a source of energy and it being used to break of Cl-Cl and
  produce Cl free radical Free radical’s which can attack methane. in dark this is not possible.

Question 28.
How will you prepare n-propyl iodide from n-propyl bromide?
Answer:
Finkeistein reaction:
n-propyl bromide on heating with a concentrated solution of sodium iodide in dry acetone gives n-propyl iodide. This S_N² reaction is called Finkelstein reaction.

Question 29.
Which alkyl halide from the following pair is –
1. chiral
2. undergoes faster S_N² reaction?

Answer:
1.

Here the C*is chiral carbon atom and it is surrounded by four different groups. Br
2.  i.e., 1-chiorohutane undergoes faster S_N² reaction. CH₃-CH₂-CH₂Cl is a primary alkyl halide and so it undergoes faster S_N² reaction.

Question 30.
How does chiorobenzene react with sodium in the presence of ether? What is the name of the reaction?
Answer:
Chiorobenzene when heated with sodium in ether solution will forrn biphenyl as the product. This reaction is called fitting reaction.

Question 31.
Give reasons for polarity of C-X bond in haloalkancs.
Answer:

• Carbon halogen bond is a polar bond as halogens are more electronegative than carbon.
• The carbon atom exhibits a partial positive change (δ⁺) and halogen atom acquires a partial negative change. (δ^–)
• 

Question 32.
Why is it necessary to avoid even traces of moisture during the use of Grignard reagent?
Answer:
Grignard reagents are highly reactive substances. They react with any source of proton to form hydrocarbons. Even water is sufficiently acidic to convert it into the corresponding hydrocarbon. So it is necessary to avoid even traces of moisture with the Grignard reagent as they arc highly reactive.

Question 33.
What happens when acetyl chloride is treated with excess of CH₃ MgI?
Answer:
When acetyl chloride is treated with excess of Grignard reagent, the product formed is tertiary butyl alcohol.

Question 34.
Arrange the following alkyl halideïniiicreasing order of bond enthalpy of RX: CH₃Br, CH₃F, CH₃Cl, CH₃I
Answer:
increasing order of bond enthalpy of RX is …………
CH₃ I bond enthalpy 234 kJ mol^-1
CH₃ Br bond enthalpy 293 kJ mol^-1
CH₃ Cl bond enthalpy 351 kJ mol^-1
CH₃ F bond enthalpy 452 IcI mol^-1
CH₃ F > CH₃ Cl> CH₃Br < CH₃ I

Question 35.
What happens when chloroform reacts with oxygen in the presence of sunlight?
Answer:
Chloroform undergoes oxidation in the presence of sunlight and air to form phosgene (carboxyl chloride)

Since phosgene is very poisonous, therefore its presence makes chloroform unfit for use as anaesthetic.

Question 36.
Write down the possible isomers of C₅H₁₁Br and give their IUPAC and common names.
Answer:
C₅H₁₁Br : 8 isomers are possible.

Question 37.
Mention any three methods of preparation of haloalkanes from alcohols.
Answer:
Haloalkanes are prepared from alcohols by treating with –

1. HCl
2. PCl₅
3. SO₂Cl₂

Answer:
1. Reaction of alcohol with hydrogen halide:

2. Reaction of alcohol with phosphorous halide:

3. Reaction of alcohol with thionyl chloride:

Question 38.
Compare S_N¹ and S_N² reaction mechanisms.
Answer:
S_N¹ Mechanism:
1. It is a unimolecular nucleophilic substitution reaction of first order.
2. It takes place in two steps.
3. It leads to racemisation.
4. It mostly take place in tertiary alkyl halides.
5. The rate of the reaction depends only on the concentration one of substrate and so it is a first order reaction.
Step – I

Step – II

S_N² Mechanism:
1. It is a bimolecular nucleophilic substitution reaction of second order.
2. It takes place in one step.
3. It leads to invertion of configuration.
4. It mostly take place in primary alkyl halides.
5. The rate of the reaction depends on the concentration of both the substrate as well as the nucleophile and so it is a second order reaction.

Question 39.
Compare S_N¹ and S_N² reaction mechanisms.

Answer:

Question 40.
Discuss the aromatic nucicophilic substitution reactions of chiorobenzene.
Answer:
Aromatic nucleophilic substitution reactions:
Dow’s process:

Question 41.
Account for the following –
1. t-butyl chloride reacts with aqueous KOH by S_N¹ mechanism while n-butyl chloride reacts with S_N² mechanism.
2. p-dichlorobenzene has higher melting point than those of o-and m-dichlorobenzene.
Answer:
1. In t-butyl chloride, there is niore steric hindrance and it involves formation of a stable tertiary carbocation. Therefore it reacts with KOH by S_N¹ mechanism rather than S_N² mechanism because S_N¹ mechanism is faourable in case of steric crowding and is directly proportional to partial positive charge on carbon atom. In n-butyl chloride, there is least steric hindrance and involves formation of less stable primary carbocation. Thus it takes place in one step and is favoured by S_N² mechanism.

2. Melting point of p – dichiorobenzene is higher than that of ortho and meta-dichiorobenzene. This is due to the fact that is has a symmetrical structure and therefore, its molecules can easily pack closely in the crystal lattice. p-dichlorobcnzene being more symmetrical fits closely in the crystal lattice and has stronger intermolecular attraction than o & m isomers. So p-isomer has high melting point than the corresponding o & m-isomers.

Question 42.
In an experiment ethyliodide in ether is allowed to stand over magnesium pieces. Magnesium dissolves and product is formed
(a) Name the product and write the equation for the reaction.
(b) Why all the reagents used in the reaction should be dry? Explain.
(c) How is acetone prepared from the product obtained in the experiment?
Answer:
(a) When ethyl iodide in ether is allowed to stand over magnesium pieces. the product formed will be Ethyl magnesium iodide.

(b) Gngnard reagent are highly reactive compounds and react with any source of proton to give hydrocarbons. Even when water is there, it is sufficiently acidic to convert it into the corresponding hydrocarbon. So it is necessary to avoid even traces of moisture with the grignard reagent as they are highly reactive. That is why the all reagents used in the reaction should be dry.

Methyl magnesium iodide reacts with acetyl chloride to form acetone.

Question 43.
Write a chemical reaction useful to prepare the following:
1. Freon- 12 from carbon tetrachioride.
2. Carbon tetrachioride from carbon disulphide.
Answer:
1. Freon-12 from carbon tetrachioride:
Freon- 12 is prepared by the action of hydrogen fluoride on carbon tetrachioride in the presence of catalytic amount of antimony pentachloride. This is called “swartz reaction”.

2. Carbon tetrachioride from carbon disuiphide:
Carbon disuiphide reacts with chlorine gas in the presence ofanhydrous AlCl₃ as catalyst to give carbon tetrachloridc.

Question 44.
What are Freons? Discuss their uses and environmental effects.
Answer:
Freons are the chiorofluoro derivatives of methane and ethane.
Freon is represented as Freon – cba
Where, c = number of carbon atoms, b = number of hydrogen atoms, a = total number of fluorine atoms.
CF₂Cl₂ = 0
c = 1 – 1 = 0
H = 0 +1 = 1
F = 2
So Freon – 12 is CF₂Cl₂

Uses of Freons:

• Freons are used as refrigerants in refrigerators and air conditioners.
• it is used as a propellant for aerosols and foams.
• it is used as propellant for foams to spray out deodorants, shaving creams and insecticides.

Environmental effects of Freons:

1. Freon gas is a very powerful greenhouse gas which means that it traps the heat normally radiated from the earth out into the space. This causes the earth’s temperature to increase, resulting in rising sea levels, droughts. stronger storms, flash floods and a host of other very unpleasant effect.

2. As freon moves throughout the air, its chemical ingredients causes depletion of ozone layer. Depletion of ozone increases the amount of ultraviolet radiations that reaches the earths surface, resulting in serious risk to human health. High levels of ozone, in turn, causes resoiratory problems and can also kill olants.

Question 45.
Predict the products when bromoethane is treated with the fòllowing:
1. KNO₂
2. AgNO₂
Answer:
1. When bromoethane is treated with KNO₂ the product formed is Ethyl nitrite.

2. When bromoethane is treated with AgNO₂ nitroethane will be formed as the product.

Question 46.
Explain the mechanism of S_N¹ reaction by highlighting the stereochemistry behind it.
Answer:
1. S_N¹ stands for unimolecular nucleophilic substitution reaction of first order reaction.
2. The rate of the following S_N¹ reaction depends upon the concentration of alkyl halide
(RX) and it is independent of the concentration of the nucicophile (OH^– ) used.
3. R-Cl + OH^– R – OH + Cl^–
4. This S_N¹ reaction follows first order kinetics and it occurs in two steps:
5. S_N¹ reaction mechanism takes place in tertiary butyl bromide with aqueous KOH a follows:

6. the 2 steps of the reaction are:
Step 1:
Formation of carbocation:
The polar C-Br bond breaks first forming a carbocation and bromide ion. This step is slow and hence it is the rate determining step.

The carbocation has two equivalent lobes of the vaccant 2p orbital, So it can react equally fast form either face.

Step 2:
The nucleophile immediately reacts with the carbocation. This step is fast and hence does not affect the rate of the reaction.

The nucleophile OH can attack carbocation from both the sides.

Question 47.
Write short notes on the the following:
1. Raschig process
2. Dows Process
3. Darzens process
Answer:
1. Raschig process:
Chiorobenzene is commercially prepared by passing a mixture of benzene vapour in air and HUt over heated cupric chloride.

2. Dow’s process:
Chiorobenzene is boiled with Sodium hydroxide to get Phenol. This reaction is called Dow’s process.

3. Darzens process:
Ethanol reacts with SOCl, in the presence of pyridine to form chloroethane. This reaction is called Darzens process.

Question 48.
Starting from CH₃MgI. How will you prepare the following’?

1. Acetic acid
2. Acetone
3. Ethyl acetate
4. Isopropyl alcohol
5. Methyl cyanide

Answer:
1. Acetic acid from grignard reagent:

2. Acetone from Gngnard reagent:

3. Ethyl acetate from Grignard reagent:

4. Isopropyl alcohol from Grignard reagent:

5. Methyl cyanide form Grignard reagent:

Question 49.
Complete the following reactions:

Answer:

Question 50.
Explain the preparation of the following compounds:

1. DDT
2. Chloroform
3. Biphenyl
4. Chioropicrin
5. Freon-12

Answer:
1. DUT

2. Chloroform:

3. Biphenyl:
Fittig reaction:

4. Chioropicrin.

5. Freon – 12.

Question 51.
An organic compound (A) with molecular formula C₂H₅Cl reacts with KOH gives compounds (B) and with alcoholic KOH gives compound (C). Identify (A), (B) and (C)
Answer:

1. An organic compound (A) of molecular formula C₂H₅Cl is identified as Chioroethane with molecular formula CH₂-CH₂Cl from the formula.

2. Chioroethane reacts with aqueous KOH to give ethanol, i.e., Aqueous C₂H₅OH as (B) by substitution reaction.

3. ChIooethane reacts with alcoholic KOH to give ethene C₂H₄ as (C) by elimination reaction.


Question 52.
Simplest alkene (A) reacts with HCl to form compound (B).Compound (B) reacts with ammonia to form compound (C) of molecular formula C₂H₂N. Compound (C) undergoes carbylarnine test. Identify (A), (B), and (C).
Answer:

1. The simplest alkene (A) is CH₂ = CH₂, ethene.

2. Ethene reacts with HCl to give Chioroethane CH₂-CH₂Cl as (B) by addition reaction.

3. Chioroethane reacts with ammonia to give Ethylamine CH₃-CH₂ NH₂ as (C). It is a primary amine and Carbylamine test is the characteristic test for 1° amine.

Question 53.
A hydrocarbon C₃H₆ (A) reacts with HBr to form compound (B). Compound (B) reacts with aqueous potassium hydroxide to give (C) of molecular formula C₃H₈O. What are (A) (B) and (C). Explain the reactions.
Answer:

1. The hydrocarbon with molecular formula C₃H₆ (A) is identified as propene,
CH₃-CH = CH₂

2. Propene reacts with HBr to form brornopropane CH₃—CH₂—CH₂Br as (B).

3. 1 -bromopropanc react with aqueous potassium hydroxide to give 1 -propanol
CH₃ – CH₂ CH₂OH as (C).

4. 2-bromo propane reacts with aqueous KOH to give 2-propanol as (C)

Question 54.
Two isomers (A) and (B) have the same molecular formula C₂H₄Cl₂. Compound (A) reacts with aqueous KOK, gives compound (C) of molecular formula C₂H₄O. Compound (B) reacts with aqueous KOH, gives compound (D) of molecular formula C₂H₆O₂. Identif’ (A), (B), (C) and (D).
Answer:

1. The compounds (A) and (B) with the molecular formula C₂H₄Cl₂ are and respectively with IUPAC names: 1, 1-dichloroethane (A) and 1.

2. 1, 1-dichloroethane reacts with aqueous KOH tp give CH₃CHO Acetaldehyde as (C).

3. 1 ,2-dichloroethane reacts with aqueous KOH to give ethylene glycol  as (D).

[Evaluate Yourself ]

Question 1.
Write the IUPAC name of the following:

Answer:

Question 2.
Write the structure of the following compounds:

1. 1-Bromo-4-cthylcyclo hexane
2. 1 4-Dichlorobut-2-ene
3. 2 Chloro-3-methyl pentane

Answer:
1. 1-Bromo-4 ethylcyclo hexane

2. 1. 4-Dichioro but-2-ene

3. 2-Çhloro-3-methyl pentane

Question 3.
Write all possible chain isomers with molecular formula C₅H₁₁Cl
Answer:
C₅H₁₁Cl:
8 isomers arc possible. These are –

Question 4.
neo-pentyl bromide undergoes nucleophilic substitution reactions very slowly. Justify.
Answer:
1.  neo-pentyl bromide undergoes nucleophilic substitution reactions very slowly due to steric hindrance of many alkyl groups. When bromide is attached to neo-pentyl carbon atom, the heterolytic cleavage of C-Br takes place very slowly and substitution is also a very slow reaction.

2. Due to bulky neo-pentyl group, it becomes difficult for a nucleophile to attack from the back side of carbon having C-Br bond.

3. Splitting of C-Br gives a primary carbocation which is very less stable. So neo-pentyl bromide undergoes nucleophilic substitution reactions very slowly.

Question 5.
Why Grignard reagent should be prepared in anhydrous condition’?
Answer:
Grignard reagent are highly reactive species and react with any source of proton to give hydrocarbons. Even when water is there, it is sufficiently acidic to convert it into the corresponding hydrocarbon. So it is necessary to avoid even traces of moisture while preparing grignard reagent as they are highly reactive and that is why gngnard reagent should be prepared in anhydrous conditions.

Question 6.
Haloalkanes undergo nucleophilic substitution reaction whereas haloarenes undergo electrophilic substitution reaction. Comment.
Answer:
Haloalkanes undergo nucleophilic substitution reactions due to high clectronegativity of the halogen atom. The C-X bond in haloalkanes is slightly polar, thereby the C atom acquires a slight positive charge in C-X bond. [lence C atom is a good target for attack for nucleophiles. Therefore C-X atom of haloalkanes is replaced by a nucleophile easily.

On the other hand in haloarenes, the halogen atom releases electron to the benzene nucleus relatively electron rich with respect to the halogen atom. As a result the electrophilic attack occurs at ortho and para positions. Hence haloarenes undergo electrophilic substitution reactions.

Question 7.
Chloroform is kept with a little ethyl alcohol in a dark coloured bottle. Why?
Answer:
1. Chlorofòrm is slowly oxidised by air in the presence of light to an extremely poisonous gas, carboxyl chloride (phosgene). it is therefore stored in closed dark coloured bottles completely filled so that air is kept out.

2. With the use of 1% ethanol we can stabilise chloroform, because ethanol can convert the poisonous COCl₂ gas into non poisonous diethyl carbonate.
COCl₂ + 2C₂H₅OH CO(OC₂H₅)₂ + 2HCl

Question 8.
What is the IUPAC name of the insecticide DDT? Why is their use banned in most of the countries?
Answer:
1. The IUPAC name of the insecticide DDT isp, p-dichloro-diphenyl trichioroethane.
2. Even DDT is an effective insecticide. Now-adays it is banned because of its long term toxic effects.
3. DDT is very persistent in the environment and it has a high affinity for fatty tissues. As a result, DDT gets accumulated in animal tissue fat, in particular that of birds of prey with subsequent thinning of their eggs shells and impacting their rate of reproduction. That is why DDT is banned in most of the countries.

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes Additional Questions Solved

I. Choose The Correct Answer.

Question 1.
Which of the following is an example for polyhalo compounds?
(a) Vnyl iodide
(b) Chiorobenzene
(c) Allyl chloride
(d) Chloroform
Answer:
(d) Chloroform

Question 2.
Which of the following is a secondary haloalkane?
(a) Bromoethane
(b) 2-Chioropropane
(c) 2-Jodo-2-methylpropane
(d) 1-Chloropropane
Answer:
(b) 2-Chioropropane

Question 3.
How many isomers are possible for the formula C₄H₉Cl?
(a) 3
(b) 2
(c) 4
(d) 5
Answer:
(c) 4

Question 4.
How many isomers are possible for the formula C₅H₁₁Br?
(a) 11
(b) 8
(c) 4
(d) 5
Answer:
(b) 8

Question 5.
Which of the following is called Lucas reagent?
(a) Conc. H₂SO₄ + Anhydrous CuSO₄
(b) Conc.HCl + Anhydrous ZnCl₂
(c) Dil.HCl + AlCl₃
(d) Conc.HCl + ConcHNO₂
Answer:
(b) Conc.HCl + Anhydrous ZnCl₂

Question 6.
Which of the following mechanism is followed in the halogenation of alkanes in the presence of U-V light?
(a) Nucleophilic substitution
(b) Electrophilic addition
(c) Free radical substitution
(d) Elimination reaction
Answer:
(c) Free radical substitution

Question 7.
The reactivity of alcohols with haloacid is –
(a) 3° > 2° > 1°
(b) 1° > 2° > 3°
(c) 2° > 3° > 1°
(d) 3° > l° > 2°
Answer:
(a) 3° > 2°> 1°

Question 8.
Which of the following reagent is not used to convert alcohol to haloalkane?
(a) H-X
(b) PX₅
(c) CCl₄
(d) SOCl₂
Answer:
(c) CCl₄

Question 9.
What is the name of the reaction in which bromoethane is converted to iodoethane by reacting with NaI in acetone?
(a) Hunsdicker reaction
(b) Dow’s process
(c) Finkelstein reaction
(d) Swarts reaction
Answer:
(c) Finkeistein reaction

Question 10.
Identify the correct order of boiling point of haloalkanes?

Answer:

Question 11.
Which of the following pair functional groups represents ambident nucleophiles?
(a)-SH-&-OH
(b)-CN-&-NO₂
(c)-Br-&-Cl
(d)-O-&-CHO
Answer:
(b)-CN & NO₂

Question 12.
Which one following mechanism will be followed when Tartiary butyl chloride is treated with alcoholic KOH?
(a) S_N¹ mechanism
(b) E₁ mechanism
(c) S_N² mechanism
(d) E₂ mechanism
Answer:
(b) E₁ mechanism

Question 13.
Which one of the following is used for producing pesticìdes?
(a) CHI₃
(b) CHCl₃
(c) CCl₃ NO₂
(d) CCl₄
Answer:
(b) CHCl₃

Question 14.
Which one of the following react with gringnard reagent followed by hydrolysis will yield primary alcohol?
(a) CH₃ CHO
(b) HCHO
(c) CH₃ COCH₃
(d) CO₂
Answer:
(b) HCHO

Question 15.
Which one of the following reacts with CH₃MgI followed by hydrolysis and gives isopropyl alcohol?
(a) CH₃ COCH₃
(b) CH₃ CHO
(c) HCHO
(d) CNCl
Answer:
(b) CH₃ CHO

Question 16.
Which one of the following reacts with CH₃ Mg I followed by hydrolysis to yield tert. butyl alchol ?
(a) CH₃CHO
(b) HCHO
(c) CH₃COOC₂H₅
(d) CH₃COCH₃
Answer:
(d) CH₃COCH₃

Question 17.
Which one of the following reacts with CH₃ Mg I followed by acid hydrolysis to yield acetic acid ?
(a) CNCl
(b) CH₃COOC₂H₅
(c) HCOOC₂H₅
(d) CO₂
Answer:
(d) CO₂

Question 18.
Which one of the following reagent react with methyl magnesium iodide followed by acid hydrolysis to give ethyl acetate?
(a) Chiorodimethyl ether
(b) Ethyl chloroformate
(c) Ethyl formate
(d) Acetaldehyde
Answer:
(b) Ethyl chioroformate

Question 19.
Which one of the following is used as fibre-swelling agent in textile processing?
(a) Chiorohenzene
(b) Chloroform
(c) Chlorai
(d) Chloroethane
Answer:
(a) Chiorobenzene

Question 20.
Which one of the fillowing is a gemdihalide?
(a) CH₃CHCl₂

(c) CH₃-CH₂Cl
(d) C₆H₄Cl₂
Answer:
(a) CH₃CHCl₂

Question 21.
Which of the following reagent is used to distinguish gem-dihalides and vicinal dihalides?
(a) Alcoholic KOH
(b) Aqueous KOH
(c) FeCl₃ / Cl₂
(d) Ethanol
Answer:
(b) Aqueous KOH

Question 22.
Which one of the following is used in the conversion of ethyliden dichioride to Acetylene?
(a) Zn + Methanol
(b) KOH + Ethanol
(c) Aqueous NaOH
(d) Alcoholic KOH
Answer:
(b) KOH + Ethanol

Question 23.
Which one of the following is used as a metal cleaning solvent?
(a) Isopropylidene chloride
(b) Methylene chloride
(c) Chloroform
(d) lodoform
Answer:
(b) Methylene chloride

Question 24.
Which one of the following is used as an insecticide and as a soil sterilising agent?
(a) Chloroform
(b) Chlorai
(c) Chioropicrin
(d) Tetrachioromethane
Answer;
(c) Chloropicrin

Question 25.
Which one of the following is used to test primary amincs?
(a) Schiff’s test
(b) Carbylarnine test
(c) Dye test
(d) Silver mirror test
Answer:
(b) Carbyianiine test

Question 26.
Which one of the following is used as propellant for aerosols and foams?
(a) Freons
(b) Methylidene chloride
(c) Chlorai
(d) Chloroform
Answer:
(a) Freons

Question 27.

the product X is –

Question 28.
Which one of the following will undergo S_N¹ reaction faster?

Answer:

Question 29.
Which one of the following compounds does not undergo nucleophilic substitution reactions at all?
(a) Ethyl bromide
(b) Vinyl chloride
(c) Benzyl chloride
(d) isopropyl chloride
Answer:
(b) Vinyl chloride

II. Match the following.

Question 1.

Answer:

Question 2.

Answer:

Question 3.

Answer:

Question 4.

Answer:

Question 5.

Answer:
“17” />

Question 6.

Answer:

III. Fill in the blanks.

Question 1.
is used in the treatment of typhoid ……….
Answer:
chloramphenicol

Question 2.
………. is used in the treatment of malaria
Answer:
Chioroquine

Question 3.
………. is used as an anesthetic ……….
Answer:
Halothane

Question 4.
………. is used for cleaning electronic equipments ……….
Answer:
Trichioroethylene

Question 5.
The IUPAC name of CH₂=CH-CH₂Cl is ……….
Answer:
3-Chioro-prop- 1-ene

Question 6.
The structure of Vinyl iodide is ……….
Answer:
CH₂=CHI

Question 7.
2-iodo-2-methylpropane belongs to type ……….
Answer:
3°haloalkanes

Question 8.
The structure of 2-Iodo-2-methylpropanc is ………
Answer:

Question 9.

the IUPAC name of this compound is ……..
Answer:
1-Bromo-2, 2-dimethyipropane

Question 10.
The IUPAC name of CH₂=CHCl is ………
Answer:
Chioroethene

Question 11.
The IUPAC name of is ………
Answer:
2-Bromo-3-chloro-2, 4-dimethylpentane.

Question 12.
The IUPAC name of is ………
Answer:
3-Chloro-2-methyl-prop- 1 -ene

Question 13.
The reactivity of haloacids (HCl , HBr, HI) with alcohol is in the order ………
Answer:
HI > HBr > HCl

Question 14.
The decreasing order of bond length among alkyl halides (CH₂I , CH₂ Br , CH₃F , CH₃Cl ) is in the order ………
Answer:
CH₃F < CH₃Cl < CH₃Br < CH₃I

Question 15.
The bond strength of C-X for the C-Cl , C-Br, C-I , C-F decreases in the order is ………
Answer:
C-F < C-Cl<C-Br < C-I

Question 16.
The catalyst used in Darzen halogenation of alcohol is ………
Answer:
Pyridine

Question 17.
In Finkeistein reaction, the mechanism followed is
Answer:
S_N²

Question 18.
Silver salt of fatty acid is converted to bromo alkanc by ………
Answer:
Hunsdicker reaction

Question 19.
In Swarts reaction, chioroalkane is converted to ………
Answer:
Fluoroalkane.

Question 20.
The conversion of bromoalkane to fluroalkane by heating with AgF is called ………
Answer:
Swartz reaction

Question 21.
The decreasing order of boiling point of haloalkanes CH₃ Br , CH₃Cl , CH₃F CH₃I is ………
Answer:
CH₃I > CH₃Br > CH₃CI > CH₃F

Question 22.
The correct increasing order of boiling point of haloalkanes CH₃Cl , CHCl₃ , CH₂Cl₂ , CCl₄ is ………
Answer:
CCl₄ > CHCl₃ > CH₂Cl₂ > CH₃Cl

Question 23.
Haloalkanes reacts with aqueous solution of KOH to form ………
Answer:
Alcohol

Question 24.
Haloalkane reacts with alcoholic solution of KOH to form ………
Answer:
Alkene

Question 25.
Ethyl bromide reacts with alcoholic AgCN to form ………
Answer:
CH₃CH₂NC

Question 26.
Ethyl bromide reacts with alcoholic KNO₂ to form ………
Answer:
Ethyl nitrite

Question 27.
The reaction in which sodium alkoxide react with haloalkane to form ether in called ………
Answer:
Williamson’s synthesis

Question 28.
Primary alkyl halide react with aqueous NaOH follows ………
Answer:
S_N²

Question 29.
Tertiary butyl bromide reacts with aqueous KOH follows ………
Answer:
S_N² mechanism

Question 30.
Ethyl bromide reacts with alcoholic KOH following mechanism. ………
Answer:
E₁

Question 31.
The product formed when tertiary butyl chloride is treated with alcoholic KOH is ………
Answer:
Iso-butylene

Question 32.
When 2-bromobutane react with alcoholic KOH, the products formed are ………
Answer;
1-butene & 2-butene

Question 33.
The product formed when iodoethane is treated with HI in the presence of red phosphorous is ………
Answer:
CH₃-CH₃

Question 34.
……… is used as an antiseptic
Answer:
Iodoform

Question 35.
……… is used for extinguishing the fire caused by oil or petrol under the commercial name pyrene
Answer:
Tetrachioromethane

Question 36.
……… Ethyl formate reacts with methyl magnesium iodide followed by acid hydrolysis to yield
Answer:
Acetaldehyde

Question 37.
……… Ethyl-methyl ether ethene is obtained by the action of methyl magnesium iodide with
Answer:
Chioro-aimethyl-ether

Question 38.
The hybridised state of carbon in haloarenes is ………
Answer:
sp²

Question 39.
The catalyst used in the preparation of chiorobenzene from benzene is ………
Answer:
FeCl₃

Question 40.
In the Gattermann reaction of preparation of chiorobenzene from benzene, the catalyst used is ………
Answer:
Cu / HCl

Question 41.
The conversion of benzene diazoniurn chloride to chiorobenzene in the presence of Cu₂Cl₂ + HCl is named as ………
Answer:
Sandmeyer reaction

Question 42.
Fluorobenzene is prepared from benzene diazonium chloride by ………
Answer:
BaIz-Scheimann reaction

Question 43.
Conversion of benzene to chiorobenzene in the presence of CuCl₂ / HCl is named as ………..
Answer:
Gattermann reaction

Question 44.
The conversion of chiorobenzene to phenol by the action of NaOH is called ………..
Answer:
Dow’s process

Question 45.
In Wurtz fittig reaction, chiorohenzene is converted to by reacting it with ethyl chloride.
Answer:
Ethylbenzene

Question 46.
The product obtained in fittig reaction of chiorobenzene is ………..
Answer:
Biphenyl

Question 47.
The reagent used in the conversion of Chiorobenzene to Benzene is ………..
Answer:
Ni-Al/NaOH

Question 48.
The catalyst used in the preparation of Phenyl magnesium chloride from chiorobenzene is ………..
Answer:
THF

Question 49.
Iso-propylidene chloride is an example of ………..
Answer:
vicinal dihalide

Question 50.
The IUPAC name of is ………..
Answer:
1, 2-dibromo-2-methylpropane

Question 51.
The reagent used in the conversion of ethylene dichioride is ………..
Answer:
Zn + CH₃OH

Question 52.
Chloroform is converted to methylene-chioride by the action of ………..
Answer:
Zn + HCl and H₂ / Ni

Question 53.
The reagents used in the preparation of chloroform are ………..
Answer:
Ethanol + Bleaching powder

Question 54.
The formula of Chioropicrin is ………..
Answer:
CCl₃NO₂

Question 55.
The product formed when methylamine react with chloroform and alkali is ………..
Answer:
CH₃NC

Question 56.
The product formed when CCI4 reacts with hot water vapours is
Answer:
COCl₂

Question 57.
The formula of Freon -11 is ………..
Answer:
CFCl₃

Question 58.
The formula of Freon – 12 is ………..
Answer:
CF₂Cl₂

Question 59.
The catalyst used in the preparation of CCl₂F₂ from CCl₄ and HF is ………..
Answer:
SbCl₅

Question 60.
The reagents used to prepare DDT are ………..
Answer:
Chlorai and Chiorobenzene

Question 61.
……….. is used to kill various insects like housefly and mosquitoes.
Answer:
(c) DDT

Question 62.
The name of CFCl₃ is
Answer:
Freon-11

Question 63.
The treatment of acetone with excess of RMgX gives:
Answer:

Question 64.
The most easily hydrolysed molecule under S_N² reaction is………..
Answer:
Ten. butyl chloride

Question 65.
. The product ‘X’ is ………..
Answer:
Ethanol

Question 66.
The product X is ………..
Answer:
CH₄

Question 67.
On heatrng CHCl₃ with aqueous NaOH solution, the product formed is
Answer:
HCOONa

Question 68.
Depletion of ozone layer is caused by
Answer:
Freons

Question 69.
Chloropicrin is used as
Answer:
soil sterilizing agent

Question 70.
lodoform can be used as
Answer:
Antiseptic.

Question 71.
in oil fire extinguisher, the compound used pyrene is chemically
Answer:
CCl₄

Question 72.
Reaction of ethyl chloride with sodium metal leads to the formation of
Answer:
n-Butane

Question 73.
When chloroform is treated with primary amine and KOH, we get ………..
Answer:
Offensive odours

IV. Choose the odd one out.

Question 1.
(a) CH₃Br
(b) CH₃-CH₂Br
(c) (CH₃)₃C-Br
(d) CH₃-CH₂-CH₂Br
Answer:
(c) (CH₃)₃C-Br. It is a haloalkane whereas others are 1° haloalkanes.

Question 2.
(a) Finkeistein reaction
(b) Wurtz reaction
(c) Swarts reaction
(d) Friedel crafts alkylation
Answer:
(d) Friedel crafts alkylation. It is used to prepare aromatic hydrocarbon whereas others are used to prepare alkanes.

Question 3.
(a) PCl₅
(b) SOCl₂
(c) HCl
(d) HF
Answer:
(cl) HF It is not used to prepare directly fluoro alkane whereas others are used to prepare directly chioro alkanes.

Question 4.
(a) Aerosol spray propellant
(b) Metal cleaning agent
(c) Anaesthetic agent
(d) Solvent in paint remover
Answer:
(c) Anaesthetic agent. It is not the use of methylene chloride whereas others are uses of methylene chloride.

V. Choose the correct pair.

Question 1.
(a) Chiorobenzene + chloral : DDT
(b) Chloroform + HNO₃ : Phosgene
(c) Chloroform + Zn / HCl : Methyl isocyanide
(d) Methane + 4Cl₂ : Carbon tetra chloride
Answer:
(c) Chlorobenzene + chloral : DDT

Question 2.
(a) Chloroform : Analgesic
(b) Freon : Propellant
(c) Chioropicrin : Antiseptic
(d) DDT : Soil sterilizing agent
Answer:
(b) Freon : Propellant

Question 3.
(a) Freon : Refrigerant
(b) DDT : Antiseptic
(c) Methylene : Soil sterilizing agent
(d) Iodotorni : Anaesthetic
Answer:
(a) Freon : Refrigerant

Question 4.
(a) HCOH + CH₃MgI : Secondary alcohol
(b) CH₃CHO + CH₃MgI : Tertiary alcohol
(c) CH₃COCH₃ + CH₃MgI : Primary alcohol
(d) CO₂ + CH₃MgI : Acetic acid
Answer:
(d) CO₂ + CH₃MgI : Acetic acid

Question 5.
(a) (C₃H)₃C-Cl + alcoholic KOH : S_N¹ reaction
(b) (CH₃)₃C-Cl + alcoholic KOH : E₁ reaction
(c) (CH₃)₃C-Cl + aqueous KOH : S_N² reaction
(cl) CH₃-Cl + aqueous KOH : S_N¹ reaction
Answer:
(b) (CH₃)₃C-Cl + alcoholic KOH : E₁ reaction

VI. Choose the incorrect pair.

Question 1.

Answer:

Question 2.
(a) CH₃I > CH₃Br > CH₃Cl > CH₃F : decreasing order of boiling point
(b) CCl₄ > CHCl₃> CH₂Cl₂ > CH₃Cl : increasing order of boiling point
(c) CH₃-CH₂-CH₂Cl <CH₃ CH₂ Cl <CH₃Cl : increasing order of boiling point

Answer:
(c) CH₃-CH₂-CH₂Cl <CH₃ CH₂Cl <CH₃Cl : increasing order of boiling point

Question 3.
(a) (CH₃)₃ C-Br + aqueous KOH : S_N¹ reaction
(b) (CH₃)₃ C-Br + alcoholic KOH: E₁ reaction
(c) CH₃Br – aqueous KOH : E₂ reaction
(d) CH₃Br + aqueous KOH : S_N² reaction
Answer:
(c) CH3Br + aqueous KOH : E₂ reaction

Question 4.
(a) 1-chioro propane + Alcoholic KOH : Propene
(b) Tert.butyl bromide + Alcoholic KOH : Isobutylenc
(c) CH₃-CH₂I + HI + Red p : Ethanc
(d) CH₃CHO + CH₃ Mg I : Ten. Butyl alcohol
Answer:
(d) CH₃CHO + CH₃ Mg I : Ten. Butyl alcohol

Question 5.
(a) HCHO + CH₃MgI : Primary alcohol
(b) CH₃CHO + CH₃MgI : Secondary alcohol
(c) CH₃COCH₃ + CH₃MgI : Aromatic alcohol
(d)CO₂ + CH₃MgI : Acetic acid
Answer:
(c) CH₃COCH₃ + CH₃MgI : Aromatic alcohol

VII. Assertion & Reason.

Question 1.
Assertion (A): The C-I in CH₃X is weak.
Reason (R): Larger the size, greater is the bond length and weaker is the bond formed.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(a) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 2.
Assertion (A): Haloalkanes have higher boiling point and melting point than the parent alkanes having the same number of carbon.
Reason (R): The intermolecular forces of attraction and dipole-dipole interactions are
stronger in haloalkanes.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 3.
Assertion (A) : Among isomenc halides, the boiling point decreases with increase in branching in alkyl group.
Reason (R) : With the increase in branching, the molecule attains spherical shape with less
surface area and less forces of interaction.
(a) Both (A) and (R) are correct and (R) is not the correct explanation of (A).
(b) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 4.
Assertion (A): The melting point of para halóbenzene is higher than that of ortho and meta isomers.
Reason (R): The higher melting point of p-isomer is due to its symmetry which leads to more close packing of its molecules in the crystal and subsequently p-isomer have strong intermolecular attractive forces.
(a) both (A) and (R) are correct and (R) is the correct explanation of(A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of(A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) both (A) and (R) are correct and (R) is the correct explanation of(A).

Question 5.
Assertion (A) : Haloarenes are insoluble in water.
Reason (R) : Haloarenes are able to form hydrogen bonds with water.
(a) Both (A) and (R) are correct but (R) is the correct explanation of (A).
(b) both (A) and (R) are correct and (R) is not the correct explanation of (A).
(e) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct
Answer:
(c) (A) is correct but (R) is wrong.

Question 6.
Assertion (A) : Haloarenes do not undergo nucleophilic substitution reactions readily.
Reason (R) : The C-X bond in aryl halides is short and stronger and also the aromatic ring is a center of high electron density.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(h) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 7.
Assertion (A): Chloroform vapours can be used as an anaesthetic.
Reason (R): Chloroform vapours depresses the central nervous system and cause unconsciousness.
(a) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(b) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 8.
Assertion (A): Nowadays chloroform is not used as an anaesthetic.
Reason (R): Chloroform undergoes oxidation in the presence of light and air to form highly poisonous phosgene.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(cl) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 9.
Assertion (A): DDT is banned now-a-days.
Reason (R): DDT has a long term toxic effect.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.
Answer:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.

VIII. Choose the correct statement.

Question 1.
(a) Halo alkanes have higher boiling point than the parent alkane with same number of carbons because of strong inter molecular forces of attraction.
(b) The boiling point of halo alkanes decreases with the increase of halogen atoms.
(c) The boiling point of mono halo alkanes decreases with the increase in the number of carbon atoms.
(d) Halo alkanes are soluble in water.
Answer:
(a) Halo alkanes have higher boiling point than the parent alkane with same number of carbons because of strong inter molecular forces of attraction.

Question 2.
(a) Halo alkanes are soluble in water.
(b) The boiling point of halo alkanes increase with the increase in the number of halogen atoms.
(c) The melting point of mono halo alkane decrease with the increase in the number of carbon atoms.
(d) The density of alkyl halides are lesser than those of hydrocarbons of comparable molecular weight.
Answer:
(b) The boiling point of halo alkanes increase with the increase in the number of halogen atoms.

Question 3.
(a) Williamson’s synthesis of ether is an example of nucleophilic substitution reaction.
(b) Reaction of methyl bromide with aqueous potassium hydroxide is an example ofelimination reaction.
(c) Reaction of Tertiary butyl bromide with alcoholic KOH is an example of SN2 reaction.
(d) Reaction of Tertiary butyl bromide with alcoholic KOH is an example of E, reaction.
Answer:
(a) Williamson’s synthesis of ether is an example of nucleophilic substitution reaction.

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes 2 Marks Questions and Answers

Question 1.
Write the IUPAC names of –

1. CH₂=CHCI
2. CH₂=CH-CH₂Br.

Answer:

1. CH₂=CHCl : Chloroethene
2. CH₂=CH-CH₂Br : 3-Bromo-prop- 1-ene

Question 2.
Write the structural formula of the following compounds:

1. 2-Chloro-2-Methylpropane
2. 1 -Bromo-2, 2-Dimethylpropane

Answer:
1. 2-Chloro-2-Methylpropane

2. 1 -Brorno-2, 2-dimethyipropane

Question 3.
How many isomers are possible for the formula C₃H₇F? Give their structures and names.
Answer:
C₃H₇F – 2 isomers are possible.
1. CH₃-CH₂-CH₂F – 1- fiuoropropene

Question 4.
Write the isomeric structures and names for the formula C₂H₄Cl₂.
Answer:

 Ethylene dichioride (or) 1, 2-dichioroethane.

Ethylidene chloride (or) 2-dichioroethane.

Question 5.
Draw the structures of –

1. 1-brorno-2, 3-dichiorobutane
2. 2-bromo-3-chloro-2, 4-dimethyl pentane

Answer:
1. 1 -bromo-2, 3-dichiorobutane

2. 2-bromo-3-chloro-2, 4-dimethy 1 pentane

Question 6.
What happens when HI reacts with ten. butyl alcohol?
Answer:

Question 7.
Explain the action of
(i) PCl₅
(ii) PCl₃ with ethanol.
Answer:

Question 8.
How does HBr react with propene?
Answer:
Propene react with HBr and follows Markovnikov’s rule.

Question 9.
How methane reacts with Cl₂ in the presence of light?
Answer:

Question 10.
Explain-Finkelstein reaction.
Answer:
Chioro (or) bromoalkane on heating with sodium iodide in dry acetone gives jodo alkane. This reaction is called Finkeistein reaction.
Answer:

Question 11.
Explain Swans reaction.
Answer:
Chioro (or) bromoalkanes on heating with AgF give fluoroalkanes. This reaction is called Swans reaction.

Question 12.
What happens when silver propionate reacts with Br, in CCl₄?
Answer:
Silver salt of fatty acids (CH₃CH₂COOAg), e.g., silver propionate treated with Br₂ / CCl₄ gives bromoalkane. This reaction is called Hunsdicker reaction.

Question 13.
Haloalkanes have higher boiling point and melting point than the parent alkane. Justify this statement.
Answer:
Haloalkanes have higher boiling point than the parent alkane having the same number of carbon atoms because the intermolecular forces of attraction and dipole-dipole interactions are comparatively stronger in haloalkanes.

Question 14.
CCl₄ > CHCl₃ > CH₂Cl₂ > CH₃Cl is the decreasing order of boiling point in haloalkanes. Give reason.
Answer:
The boiling point of chioro, bromo and iodoalkanes increases with increase in the number of halogen atoms. So the correct decreasing order of boiling point of haloalkanes is:
CCl₄> CHCl₃ > CH₂Cl₂> CH₃Cl.

Question 15.
Arrange the following in increasing order of boiling point. Give reason.
(CH₃CH₂CH₂Cl, CH₃CH₂Cl, CH₃Cl)
Answer:
The correct order of boiling point of haloalkanes is:
CH₃CH₂CH₂Cl > CH₃CH₂Cl > CH₃Cl.
The boiling point of monoalkanes increase with the increase in the number of carbon atoms.

Question 16.
Why haloalkanes arc insoluble in water but soluble in organic solvents?
Answer:
Haloalkanes are polar covalent compounds, soluble in organic solvents, but insoluble in water because they are unable to form hydrogen bond with water molecules.

Question 17.
What happens when bromoethane is treated with moist silver oxide?
Answer:
When bromoethane is treated with moist silver oxide, ethanol will be formed as product:

Question 18.
Complete the following reactions:

Answer:

Question 19.
Explain the action of sodium hydrogen suiphide with bromoethane?
Answer:

Question 20.
Explain Williamson’s synthesis.
Answer:
Williamson’s synthesis:
Haloalkanes when boiled with sodium alkoxide gives the corresponding ether.

Question 21.
Explain the action of alcoholic potash with bromoethane.
Answer:
Elimination reaction takes place when alcoholic potash reacts with bromoethane:

Question 22.
State-Saytzeff’s rule.
Answer:
Some haloalkanes when treated with alcoholic KOH yield a mixture of olefins with different amounts. It is explained by Saytzeff’s rule which states that in a dehydrohalogenation reaction, the preferreed product is that alkene which has more number ofalkyl group attached to the doubly bonded carbon atom.

Question 23.
How will you convert 1-chioropropanc to propene?
Answer:

Question 24.
What is Grignard reagent? How is it prepared from ethyl bromide?
Answer:
When a solution of haloalkane in either is treated with magnesium, we will get alkyl magnesium halide known as Grignard reagent, ethyl magnesium bromide is prepared from ethyl bromide as:

Question 25.
How will you prepare ethyl lithium’?
Answer:
When bromoethane is treated with an active metal like lithium in the presence of dry ether, then ethyl lithium will be formed.

Question 26.
What is tetraethyl Lead? How is it prepared?
Answer:

Question 27.
Convert bromoethane to ethane.
Answer:

Question 28.
How is iodoethane converted to ethane?
Answer:

Question 29.
Starting from CH₃MgI, how will you prepare acetaldehyde?
Answer:

Question 30.
How will you get acetone from methyl manesium iodide?
Answer:

Question 31.
Explain the action of Ethyl chioroformate with Methyl magnesium iodide.
Answer:
Ethyl chioroformate reacts with Grignard reagent to form esters as follows:

Question 32.
Write the IUPAC names of:

Answer:
1 – bromo-4-fluoro-2-iodobenzene
1 – bromo-2-fluoro-4-iodobenzene

Question 33.
How is benzene directly converted to chiorobenzene?
Answer:

Question 34.
Explain Sandmeyer’s reaction.
Answer:
Sandmeyer’s reaction:
The reaction in which benzene-diazonium chloride is converted to chiorobenzene on heating it with Cu₂Cl₂/HCl is known as sand Meyer’s reaction.

Question 35.
Explain Gattcrrnann reaction.
Answer:
Gattermann reaction:
The reaction in which benzene diazonium chloride react with copper in the presence of HCl, chlorobenzene is formed, called Gatterrnann reaction.

Question 36.
How will you prepare iodobenzene?
Answer:

Question 37.
Explain-Balz-Schiernann reaction.
Answer:
Fluorobenzene is prepared by treating benzene diazonium chloride with fluoro boric acid. This reaction produces diazonium fluoroborate which on heating produce fluorobenzene. this reaction is called Balz-Schiernann reaction.

Question 38.
p-dichlorobenzcnc has higher melting point than ortho and meta dichloro benzene. Why?
Answer:
The melting point of p-dichloro benzene is higher than the melting point of the corresponding ortho and mcta isomers. The higher melting which leads to more close packing of its molcules in the crystal lattice and consequently strong intermolecular attractive forces which requires more energy for melting.
p-dichlorobenzene > o-dichlorobenzene > m-dichlorobenzene

Question 39.
Explain Wurtz-fìtting reaction.
Answer:
Wurtz-fitting reaction:
Chlorobenzene and chioroethane are heated with sodium in ether solution to form ethylbenzene. This reaction is called Wurtz-fìtting reaction.

Question 40.
How will you get benzene from chlorobenzene?
Answer:
Chiorobenzene is reduced with Ni-Al Alloy in the presence of NaOH to give benzene.

Question 41.
Explain about the preparation of phenyl magnesium chloride.
Answer:

Question 42.
How will you prepare ethylidcne dichioride from acetylene?
Answer:

Question 43.
What is gern-dihalide? Give one example and explain its preparation.
Answer:
1. If two halogen atoms are attached to one carbon atom of alkyl halide, it is named as gem dihalide. e.g., CH₃-CHCl₂ (ethylidene dichloride.)

2. Preparationof CH₃-CHCl₂:

Question 44.
Explain the action of zinc and HCl on chloroform.
Answer:

Question 45.
How does nickel react with chloroform?
Answer:

Question 46.
Convert methane to methylene chloride.
Answer:

Question 47.
Explain Carbylamine reaction. (or) Give the characteristic test for primary amine.
Answer:
Chlorofonn reacts with aliphatic or aromatic primary amines and alcoholic caustic potash to give foul smelling alkyl isocyanide (carbylamine).

Question 48.
How will you prepare carbon tetrachioride?
Answer:
The reaction of methane with excess of chlorine in the presence of sunlight give carbon tetrachioride as major product.

Question 49.
How will you convert carbon tetrachioride to chloroform?
Answer:

Question 50.
What are freons? How are they named? Give two examples.
Answer:
(i) The chioro-fluoro derivatives of methane and ethane are called freons.
(ii) Freon is represented as freon-cba
c = number of C atoms –
b = number of H atoms + 1
a = total number ofF atoms

Question 51.
What are ambident nucleophiles’? Explain with an example.
Answer:
Nucleophiles which can attack through two different sites are called ambident nucicophiles. For example, cyanide group is a resonance hybrid of two contributing structures and therefore it can act as a nucleophile in two different ways:

It can attack through carbon to form cyanides and through nitrogen to form isocyanides or carbylamines.

Question 52.
Which compound in each of the following pairs will react faster in S_N² reaction with OH ion?
1. CH₃Br or CH₃I
2. (CH₃)₃CCl or CH₃Cl
Answer:
1. Since I^– ion a better leaving group than Br^– ion, therefore CH₃I will react faster than CH₃Br in S_N² reaction with OH^– ion.
2. On steric grounds 1° alkyl halides are more reactive than tert alkyl halide in S_N² reactions. Therefore, CH₃Cl will react at a faster rate than (CH₃)₃CCl in a S_N² reaction with OH^– ion.

Question 53.
The treatment ofalkyl chlorides with aqueous KOH solution leads to the formation of alcohols but in the presence of alcoholic KOH solution, alkenes are the major product. Explain.
Answer:
In aqueous solution, KOH is almost completely ioniscd to give OH^– ions which being a strong nucleophile brings about a substitution reaction of alkyl halides to form alcohols. In aqueous solution, OH^– ions are highly hydrated. This solvation reduces the basic character of OH^– ions which therefore, abstract fails to abstract a hydrogen atom from the n-carbon of the alkyl chloride to form an alkene. In contrast, an alcoholic solution of KOH contains alkoxide (RO^–) ions which being a much stronger base than OH^– ions preferentially eliminates a molecule of HCl from an alkyl chloride to form alkenes.

Question 54.
Give one example of each of the following reactions:
1. Wurtz Reaction
2. Wurtz – Fittig reaction
Answer:
1. Wurtz Reaction:
It involves conversion of alkyl halides into alkane.
Example:

2. Wurtz-Fittig reaction:
It involves the reaction of an aryl halide and alkyl halide to form the corresponding hydrocarbon.

Question 55.
How will you distinguish between the following pair of compounds:
1. Chloroform and carbon tetrachioride,
2. Benzyl alcohol and chiorobenzene.
Answer:
1. On heating chloroform and carbon tetrachloride with aniline with ethanoic acid and potassium hydroxide separately, chloroform forms a pungent smelling isocyanide compound but carbon tetrachloride does not form this compound.

2. On adding sodium hydroxide and silver nitrate to both the compounds, benzyl chloride forms a white precipitate but chiorobenzene does not form any white precipitate.

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes 3 Marks Questions And Answers

Question 1.
Give one example with structure and name for each of the following compounds.
(a) Primary haloalkane
(b) Secondary haloalkane
(c) Tertiary haloalkane
Answer:
(a) Primary haloalkane

(b) Secondary haloalkane

(c) Tertiary haloalkane

Question 2.
Write the possible isomers for the formula C₄H₉Cl with structures and names.
Answer:
C₄H₉Cl (4 isomers):

Question 3.

Answer:
For a compound with molecular formula C₄H₉Cl – 3 isomers (1°, 2°, 3°) arc possible. Among the isomeric alkyl halides, the boiling point decreases with the increase in branching in the alkyl chain. This is because with increase in branching, the molecule attains spherical shape with less surface area. As a result, the intermolecular forces become weak, resulting in lower boiling point. Therefore the boiling point decreases in the order:

Hence, (CH₃)₃ C-Cl has the lowest boiling point.

Question 4.
Explain ammonolysis of haloalkanes. (or) How excess of haloalkanc react with alcoholic ammonia?
Answer:
With excess of haloalkanes, ammonia react to give primary, secondary, tertiary amines along with quarternary ammonium salt:

Question 5.
Explain how bromoethane reacts with –
1. alcoholic KCN
2. alcoholic AgCN
Answer:
1. Bromoethanc reacts with alcoholic KCN to form ethyl cyanide.

2. Bromoethane reacts with alcoholic AgCN to form alkyl isocyanide.

Question 6.
Explain the hydrolysis of 2-bromobutane with aqueous KOB.
Answer:

• 2-bromobutane is optically active and it undergoes S_N¹ reaction with aqueous KOH.
• The product obtained will be an optically inactive racemic mixture.
• As nucleophilic reagent OH^– ion can attack the carbocation from both sides to form equal proportions of dextro and levo rotatory optically active isomers, it results in the formation of optically inactive racemic mixture.

Question 7.
Explain the action of alcoholic KOH with 2-bromobutanc.
Answer:

According to Saytzcff’s rule, when 2-bromobutanc reacts with alcoholic KOK, yields a mixture of olefins in different amounts.

(ii) In a dehydrohalogenation reaction, the preferred product is that alkene which has more number of alkyl groups attached to the doubly bonded carbon alkene.

Question 8.
Mention the uses of chloroform.
Answer:

• Chloroform is used as a solvent in pharmaceutical industry.
• It is used for producing pesticides and drugs.
• It is used as an anaesthetic.

Question 9.
What are the uses of carbon tetrachioride?
Answer:

• Carbon tetrachioride in used as a dry cleaning agent.
• It is used as a solvent for oils, fats and waxes.
• As the vapours of CCl₄ is non-combustible, it is used under the name pyrene for extinguishing the fire caused by oil (or) petrol.

Question 10.
What are ogranometallic compounds? Give one example. Explain the nature of carbon-metal bond.
Answer:

• Organometallic compounds are organic compounds in which there ¡s a direct carbon-metal bond.
• Example :  CH₃MgI. methyl magnesium iodide.
• The carbon-magnesium bond in Grignard reagent is covalent but highly polar. The carbon atom is more electronegative than magnesium. Hence, the carbon atom has partial negative charge and magnesium atom has a partial positive charge.
  

Question 11.
How would you prepare acetic acid from methyl magnesium iodide?
Answer:
Solid carbon dioxide reacts with grignard reagent to form addition product which on hydrolysis yields acetic acid.

Question 12.
Explain the nature of C-X bond in haloarenes and its resonance structure.
Answer:

1. In haloarenes, the carbon atom is sp² hybridised. The sp² hybridised orbitais arc shorter and holds the electron pair bond more.
2. Halogen atom contains p-orbital with lone pair of electrons which interacts with π – orbitaIs of berizene ring to form extended conjugated system of π – orbitals.
3. The delocalisation of these electrons give double bond character to C-X bond. The resonance structure of halobenzene are given as:
   

Question 13.
Compare the bond length C-X in haloarenes and C-X in haloalkanes.
Answer:
1. Due to this double bond character of C-X bond in haloarenes, the C-X bond length is shorter length and stronger than in haloalkanes.
2. Example:

Question 14.
What are the uses of chlorobenzene?
Answer:

• Chiorobenzene is used in the manufacture of pesticides like DDT.
• It is used as high boiling solvent in organic synthesis.
• It is used as a fibre – swelling agent in textile processing.

Question 15.
What are polyhalogen compounds? Give its types with example.
Answer:

1. Carbon compounds containing more than one halogen atom are called polyhalogen compounds.
2. They are classified as
   • gem dihalides
   • Vicinal dihalides.

(a) Gem dihalide:
In this compound, two halogen atoms are attached to one carbon atom.
e.g, CH₃CHCl₂ – ethylidene chloride.

(b) Vicinal dihalide:
In this compound, two halogen atoms are attached to two adjacent carbon atoms.
1,2-dichloroethane

Question 16.
Give two examples for –
1.  gem dihalide
2. vicinal dihalide.
Answer:
1. Gem dihalides:

2. Vicinal dihalides:

Question 17.
Explain two methods of preparation of ethylene diehioride.
Answer:
1. Addition of Cl₂ to Ethylene:

2. Action of PCl₅ on Ethylene glycol:

Question 18.
How would you distinguish gern-dihalides and iinal dihalides?
Answer:
(i) Gem-dihalides on hydrolysis with aqueous KOH gives an aldehyde or a ketone whereas vicinal dihalides on hydrolysis with aqueous KOH give glycols.

The above reaction can be used to distinguish between gem-dihalides and vicinal dihalides.

Question 19.
Explain the action of metallic zinc with –
(i) Ethylidene dichioride
(ii) Ethylene dichloridc.
Answer:

Question 20.
What happens when alcoholic KOH is treated with
(i) Ethylidene dichioride
(ii) Ethylene dich I onde?
Answer:
(i) Gem-dihalides and vicinal dihalides both on treatment with alcoholic KOH give alkynes.

Question 21.
What are the uses of methylene chloride?
Answer:
Methylene chloride is used as:

• Aerosol spray propellant.
• Solvent in paint remover.
• Process solvent in the manufacture of drugs.
• A metal cleaning agent.

Question 22.
Explain the laboratory preparation of chloroform.
Answer:
Haloform reaction:
Chloroform is prepared in the laboratory by the reaction between ethyl alcohol with bleaching powder followed by the distillation of the final product chloroform. Bleaching powder acts as a source of chlorine and calcium hydroxide. The reaction take place in 3 steps.
Step 1:
Oxidation-

Step 2:
Chlorination-

Step 3:
Hydrolysis-

Question 23.
What is chloropicrin? How is it obtained? Mention its uses.
Answer:
1. Chioropicrin is CCl₃NO₂.

2. Chloroform reacts with nitric acid to form chioropicrin (trichioro-nitromethane):

3. Chioropicrin is used as an insecticide and soil sterilising agent.

Question 24.
What are the uses of freons?
Answer:

• Freons are used as refrigerants in refrigerators and air conditioners.
• It is used as a propellant for foams and aerosols.
• It is used as a propellant for foams to spray out deodorants, shaving creams and insecticides.

Question 25.
What is DDT? How is it prepared’?
Answer:
(i) DDT is p, p’-dichloro-diphenyi-trichloroethane
(ii) DDT can be prepared by heating a mixture of chloro benzene with chlorai in the presence of conc. H₂SO₄

Question 26.
Mention the uses of DDT.
Answer:

• DDT is used lo control certain insects which carries diseases like malaria and yellow fever.
• It is used in farms to control some agricultural pests.
• It is used in building construction as pest control agent.
• It is used to kill certain kind of insects like housefly and mosquitoes due to its high and specific toxicity.

Question 27.
Write the equations for the preparation of I-iodobutane from:
(i) 1 -butanol
(ii) 1 -chiorobutane
(iii) but- 1-ene
Answer:

Question 28.
Explain why:

1. the dipole moment of chiorobenzene is lower than that of cyclohexyl chloride?
2. alkyl halides though polar, are immiscible with water?
3. Gringard reagents should be prepared under anhydrous conditions?

Answer:

1. Chlorobenzene is stabilised by resonance and there is negative charge on ‘Cl’ in 3 out of 5 resonating structures, therefore it has a lower dipole moment than cyclohexyl chloride in which there is no such negative charge.
2. Alkyl halides cannot form H-bond with water and cannot break H-bonds between water molecules, therefore they are insoluble in water.
3. Grignard reagents react with H₂O to form alkanes, therefore they are prepared under anhydrous conditions.

Question 29.
Explain as to why haloarenes arc much less reactive than haloalkanes towards nucleophilic substitution reactions?
Answer:
Haloarenes are much less reactive than haloalkanes towards nucleophilic substitution reactions due to the following reasons:

1. Resonance effect:
In haloarenes the electron pair on the halogen atom is in conjugation with the π – electrons of the ring and the following resonating structures are possible. C-Cl bond acquires a partial double bond character due to resonance. As a result, the bond cleavage in haloarenes is difficult than in case of haloalkanes and therefore they are less reactive towards nucleophilic substitution reactions.

2. The C-Cl bond length in haloalkanes is 177 pm while in haloarenes it is 169 pm. Since it is difficult to break shorter bond than a longer bond. Therefore, haloarenes are less reactive than haloalkanes towards nucleophilic substitution reactions.

Question 30.
Do the following conversions:
(i) Methyl bromide to acetone
(ii) Benzyl alcohol to 2-phenylacetic acid
Answer:

Question 31.
Give reasons for the following:

1. Ethyl iodide undergoes S_N² reactions faster than ethyl bromide.
2. (±) 2-Butanol is optically inactive.
3. C-X bond length in halobenzene is smaller than C-X bond length in CH₃-X.

Answer:

1. Because in ethyl iodide, iodide being the best leaving group among all the halide ions. Rate of S_N² reaction ability of leaving group.
2. (±) 2-hutanol is a racemic mixture which is optically inactive due to the external compensation.
3. Due to resonance in halobenzene, it has a smaller bond length value as compared to CH₃-X.

Question 32.
Write the structure of diphenyl. How is it prepared from chlorobcnzene?

Answer:

Samacheer Kalvi 11th Chemistry Haloalkanes and Haloarenes 5 Marks Question And Answers

Question 1.
Explain the classification of organic compounds with example.
Answer:

Question 2.
Explain S_N² mechanism with suitable examples.
Answer:

• S_N² reaction means bimolecular nucleophilic substitution reaction of second order.
• The rate of S_N² reaction depends upon the concentration of both alkyl halides and the nucleophile.
• This reaction involves the formation of a transition state in which both the reactant molecules are partially bonded to each other. The attack of nucleophile occurs from the back side.
• The carbon at which substitution occurs has inverted configuration during the course of reaction just as an umbrella has the tendency to invert in a wind-storm. This inversion of configuration is called walden inversion.
  

Question 3.
S_N² reaction of an optically active haloalkane is accompanied by inversion of configuration at the asymmetric centre. Prove it.
Answer:
1. S_N² reaction of an optically active haloalkane (e.g., 2-bromo-octane) is accompanied by inversion of configuration at the asymmetric center.

2. When 2-bromooctane is heated with sodium hydroxide, 2-octanol is formed with inversion of configuration. (-) 2-bromo-octane on heating with sodium hydroxide gives (+) 2-octanol is formed in which -OH group occupies a position opposite to what bromine had occupied in the optically active haloalkane.

Question 4.
Explain E₂ reaction mechanism with a suitable example.
Answer:

• E₂ reaction stands bimolecular elimination reaction of second order. The rate of E₂ reaction depends on the concentration of alkyl halide and the base.
• Primary alkyl halide undergoes this reaction in the presence of alcoholic KOH.
• It is a one step process in which the abstraction of the proton from the 3 carbon atom and expulsion of halide from the x carbon atom occur simultaneously.
• The mechanism that follows is shown below:
  

Question 5.
Describe E₁ reaction mechanism with a suitable example.
Answer:
1. E₁ stands for unimolecular elimination reaction of first order.
2. Tertiary alkyl halides undergoes elimination reaction in the presence of alcoholic KOH.
3. It takes place in two steps.
4.  Step 1.
Heterolytic fission to yield a carbocation:

5. Step 2.
Elimination of a proton from the fl-carbon to produce an alkene:

Question 6.
Starting from methyl magnesium iodide how would you prepare –

1. Ethanol
2. 2-propanol
3. Tert-butyl alcohol.

Answer:
1. Ethanol:
Formaldehyde reacts with CH₃MgI to give an addition product which on hydrolysis yields ethanol.

2. 2-Propanol :
Acetaldehyde react with CH₃MgI to give an addition product which on hydrolysis yields 2-propanol.

Question 7.
Starting from methyl magnesium iodide, how would you prepare –

1. Ethyl methyl ether
2. methyl cyanide
3. methane.

Answer:
1. Ethyl methyl ether:
Lower halogenated ether reacts with grignard reagent to form higher ether.

2. Methyl cyanide:
Grignard reagent reacts 4rith cyanogen chloride to form alkyl cyanide.

3.  Methane:
Grignard reagent reacts with waler to give methane as product.

Question 8.
Describe electrophilic substitution reaction of chiorohenzene with equations.
Answer:

Question 9.
An organic compound Ⓐ of molecular formula C₃H₆ react with HBr in the presence of peroxide to give C₃H₇Br as Ⓑ Ⓑ on reaction with aqueous KOH gives © with molecular formula C₃H₈O. Identify Ⓐ Ⓑ and ©
Answer:
1. An organic compound Ⓐ of molecular formula C₃H₆ is CH₃-CH=CH₂, Propene

2. Propene Ⓐ reacts ith HRr in the presence of peroxide to give 1-bromopropane

3. 1-Bromopropane on reaction with aqueous KOH undergoes hydrolysis to give  Propan- 1-ol. CH₃-CH₂-CH₂OH as ©

Question 10.
An organic compound Ⓐ of molecular formula C₂H₆O reacts with thionyl chloride in the presence of pyridine gives Ⓑ C₂H₅Cl. Ⓑ on reaction with alcoholic KOH gives Ⓒ, C₂H₄. Ⓒ on treatmeni with Cl₂ gives C₂H₄Cl₂ as Ⓓ. Identify Ⓐ Ⓑ Ⓒ Ⓓ and explain the reaction.
Answer:
1. An organic compound Ⓐ of molecular formula C₂H₆O is Ethanol CH₃-CH₂OH.

2. Ethanol reacts with thionyl chloride in the presence of pyridine to give CH₃-CH₂Cl Ⓑ as product.

3. Ethyl chloride on treatment with alcoholic KOH, undergoes dehydrohalogenation to give C₂H₄, ethylene Ⓒ as the product.

4. Ethylene on reaction with Cl₂ yield ethylene dichioride as Ⓓ as the product.

Question 11.
The simplest aromatic hydrocarbon C₆H₆ reacts Ⓑ on treatment with sodium hydroxide will (C₆H₅OH), Phenol, Ⓒ as the product. Also Cl₂ to give Ⓐ which on reaction with sodium hydroxide gives Ⓑ.Ⓑ of molecular formula C₆H₆O. Ⓑ on treatment with ammonia will give C₆H₇N as D. Identify Ⓐ, Ⓑ,Ⓒ, and explain the reactions involved.
Answer:
1. The aromatic hydrocarbon Ⓑ is Benzene, C₆H₆.

2. Benzene reacts with Cl, to give chiorobenzene (C₆H₅Cl), as Ⓑ as the product.

3. Chiorobenzene Ⓑ reacts with sodium hydroxide to give (C₆H₅OH) phenol, Ⓒ as the product.

4. Chiorobenzene reacts with ammonia to give Aniline, C₆H₅NH₂ Ⓓ as the product.
Question 12.
An organic compound Ⓐ of molecular formula C₂H₂ reacts with HCl to give C₂H₄Cl₂ as Ⓑ. Ⓑ on reaction with aqueous KOH will give C₂H₄O as Ⓒ Identify Ⓐ, Ⓑ,Ⓒ and explain the reactions involved.
Answer:
1. An organic compound Ⓐ of molecular formula C₂H₂ is CH ≡ CH (Acetylene)

2. Acetylene Ⓐ reacts with HCl to give ethylene dichioride Ⓑ as the product.

3. Ethylidene dichioride on reaction with aqueous KOH will give acetaldehyde, © as the product.

Question 13.
Two isomers of formula C₄H₉Br are Ⓐ and B. Ⓐ on reaction with alcoholic KOH gives of molecular formula C₈H₈ by E₁ reaction. Ⓑ on reaction with alcoholic KOH gives Ⓓ and Ⓔ as products by Saytzefì’s rule. Idcnti’ A, B, C, D, E.
Answer:
1. C₄H₉Br: Two isomers may be there: Tert butyl bromide and

2. Ⓐ on reaction with alcoholic KOH gives iso butylene © as the product.

3. 2-bromobutane Ⓑ on reaction with alcoholic KOH follows Saytzeff s rule to give a mixture of olefins in different amounts.

Question 14.
A simple aromatic hydrocarbon Ⓐ reacts with Cl₂ to give Ⓑ of molecular formula C₆H₅Cl. Ⓑ on reaction with ethyl chloride along with sodium metal gives © of formula C₈H₁₀. © alone reacts with Na metal in the presence of ether to give Ⓓ C₁₂H₁₀. Identify Ⓐ Ⓑ Ⓒ & Ⓓ
Answer:
1. The simple aromatic hydrocarbon is C₆H₆. Benzene (A)

2. Benzene reacts with Cl₂ to give chiorobenzene.

3. Chiorobenzene reacts with ethyl chloride to form ethyl benzene, © as the product

4. Chiorobenzene on reaction Na metal gives Biphenyl compound © as the product.

Question 15.
An organic compound Ⓐ of molecular formula CH₂O reacts with methyl magnesium iodide followed by acid hydrolysis to give Ⓑ of moLecular formula C₂H₆O. Ⓑ on reaction with PCl₅ gives Ⓑ. © on reaction with alcoholic KOK gives Ⓓ an alkene as the product. Identif’ Ⓐ Ⓑ Ⓒ Ⓓ and explain the reactions involved.
Answer:
1. Ⓐ of molecular formula CH₂O is identified as HCHO, formaldehyde.

2. Formaldehyde reacts with CH₃MgI followed by hydrolysis to give ethanol, CH₃-CH₂OH B as the product.

3. Ethanol Ⓑ reacts with PCl₅ to give C₂H₅Cl, Ethyl chloride © as the product.

4. CH₃-CH₂Cl © on reaction with alcoholic KOH undergoes dehydrohalogenation to give ethylene CH₂=CH₃ Ⓓ as the product.

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Samacheer Kalvi 11th Chemistry Hydrocarbons Textual Evaluation Solved

Samacheer Kalvi 11th Chemistry Hydrocarbons Multiple Choice Questions.

Question 1.
The correct statement regarding the comparison of staggered and eclipsed conformations of ethane is ……….. [NEET]
(a) the eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain.
(b) the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
(c) the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain.
(d) the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has no torsional strain.
Answer:
(b) the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.

Question 2.
The above reaction is an example of which of the following?
(a) Reirner Tiemann reaction
(b) Wurtz reaction
(c) Aldol condensation
(d) Hoffmann reaction
Answer:
(b) Wurtz reaction

Question 3.
An alkyl bromide (A) reacts with sodium in ether to form 4, 5-diethyloctane, the compound (A) is ……….
(a) CH₃(CH₂)₃Br
(b) CH₃(CH₂)₅Br
(c) CH₃(CH₂)₃CH(Br)CH₃



Answer:

Question 4.
The C-H bond and C-C bond in ethane are formed by which of the following types of overlap ………..
(a) sp³ – s and sp³ – sp³
(b) sp² – s and sp³ – sp³
(c) sp – sp and sp – sp
(d) p – s and p – p
Answer:
(a) sp³ – s and sp³ – sp³

Question 5.
In the following reaction
the major product obtained is ………

Answer:

Question 6.
Which of the following is optically active?
(a) 2 – Methylpentane
(b) Citric acid
(c) Glycerol
(d) none of these
Answer:
(a) 2 – Methylpentane

Question 7.
The compounds formed at anode in the electrolysis of an aqueous solution of potassium acetate are ……….
(a) CH₄ and H₂
(b) CH₄ and CO₂
(c) C₂ H₆ and CO₂
(d) C₂ H₆ and Cl₂
Answer:
(c) C₂ H₆ and CO₂

Question 8.
The general formula for cycloalkanes is …………
(a) C_nH_n
(b) C_nH_2n
(c) C_nH_2n-2
(d) C_nH_2n+2
Answer:
(b) C_nH_2n

Question 9.
The compound that will react most readily with gaseous bromine has the formula ………….[NEET]
(a) C₃H₆
(b) C₂H₂
(c) C₄H₁₀
(d) C₂H₄
Answer:
(a) C₃H₆

Question 10.
Which of the following compounds shall not produce propene by reaction with HBr followed by elimination (or) only direct elimination reaction? [NEET]

(b) CH₃ – CH₂ – CH₂ – OH
(c) H₂C – C = O
(d) CH₃ – CH₂ – CH₂Br
Answer:
(c) H₂C = C = O

Question 11.
Which among the following alkenes on reductive ozonolysis produces only propanone?
(a) 2 – Methylpropene
(b) 2 – Methylbut – 2 – ene
(c) 2, 3 – Dimethylbut – 1 – ene
(d) 2, 3 – Dimethylbut – 2 – ene
Answer:
(d) 2, 3 – Dimethylbut – 2 – ene

Question 12.
The major product formed when 2 bromo – 2 – methylbutane is refluxed with ethanolic KOH is ……..
(a) 2 – methylbut – 2 – ene
(b) 2 – methylbutan – 1 – ol
(c) 2 – methyl but – 1 – ene
(d) 2 – methylbutan -2- ol
Answer:
(a) 2 – methylbut – 2 – ene

Question 13.
Major product of the below mentioned reaction is ……….

(a) 2 – chloro – 1 – iodo – 2 – methylpropane
(b) 1 – chloro – 2 – iodo – 2 – methylpropane
(c) 1 ,2 – dichioro – 2 – methylpropane
(d) 1, 2 diiodo 2 – methylpropane
Answer:
(a) 2 – chioro – 1 – lodo – 2 – methylpropane

Question 14.
The IUPAC name of the following compound is ………

(a) trans – 2 – chloro-3 iodo – 2 – pentane
(b) cis – 3 – iodo – 4 – chloro – 3 – pentane
(c) trans – 3 – iodo – 4 – chloro – 3 – pentene
(d) cis – 2 chloro – 3 – lodo -2 – pdntene
Answer:
(a) trans -2 – chloro -3 – iodo – 2 – pentane

Question 15.
cis – 2 – butene and trans – 2 – butene are ……….
(a) conformational isomers
(b) structural isomers
(c) configurational isomers
(d) optical isomers
Answer:
(c) configurational isomers

Question 16.
Identify the compound (A) in the following reaction.


Answer:

Question 17.
where a is ………
(a) Zn
(b) Conc. H₂SO₄
(c) Alc. KOH
(d) Dil. H₂SO₄
Answer:
(c) Alc. KOH

Question 18.
Consider the nitration of benzene using mixed conc. FeSO₄ and HNO₃, if a large quantity of KHSO₄ is added to the mixture, the rate of nitration will be ………
(a) unchanged
(b) doubled
(c) faster
(d) slower
Answer:
(d) slower

Question 19.
In which of the following molecules, all atoms are co-planar?

Answer:
(d) both (a) and (b)

Question 20.
Propyne on passing through red hot iron tube gives ………

Answer:

Question 21.


Answer:

Question 22.
Which one of the following is non-aromatic?

Answer:

Question 23.
Which of the following compounds will not undergo Friedal – crafts reaction easily? [NEET]
(a) Nitrobenzene
(b) Toluene
(c) Cumene
(d) Xyiene
Answer:
(a) Nitrobenzene

Question 24.
Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating?
(a) – COOH
(b) – NO₂
(c) – C N
(d) – SO₃H
Answer:
(b) – NO₂

Question 25.
Which of the following can be used as the halide component for friedal – crafts reaction?
(a) Chiorobenzene
(b) Bromobenzene
(c) Chloroethene
(d) Isopropyl chloride
Answer:
(d) Isopropyl chloride

Question 26.
An alkane is obtained by decarboxylation of sodium propionate. Same alkane can be prepared by ……..
(a) Catalytic hydrogenation of propene
(b) action of sodium metal on iodomethane
(c) reduction of 1 – chloropropane
(d) reduction of bromomethane
Answer:
(b) action of sodium metal on iodomethane

Question 27.
Which of the following is aliphatic saturated hydrocarbon?
(a) C₈H₁₈
(b) C₉H₁₈
(c) C₈H₁₄
(d) All of these
Answer:
(a) C₈H₁₈

Question 28.
Identify the compound ‘Z’ in the following reaction.

(a) Formaldehyde
(b) Acetaldehyde
(c) Formic acid
(d) None of these
Answer:
(a) Formaldehyde

Question 29.
Peroxide effect (Kharasch effect) can be studied in case of ………
(a) Oct – 4 – ene
(b) Hex – 3 – ene
(c) Pent – 1 – ene
(d) But – 2 – ene
Answer:
(a) Pent – 1 – ene

Question 30.
2 – butyne on chlorination gives ………
(a) 1 – chlorobutane
(b) 1, 2 – dichlorobutane
(c) 1, 1, 2, 2 – tetrachlorobutane
(d) 2, 2, 3, 3 – tetrachlorobutane
Answer:
(d) 2, 2, 3, 3 tetra chiorobutane

Samacheer Kalvi 11th Chemistry Hydrocarbons Short Answer Questions

Question 31.
Give IUPAC names for the fllowing compounds …………
(i) CH₃ CH = CH – CH= CH – C ≡C – CH₃
(ii)

(iii) (CH₃)₃ C-C≡C-CH (CH₃)₂
(iv) Ethyl – isopropyl – acetytene
(v) CH≡C – C = C – C≡CH
Answer:

Question 32.
Identify the compound A. B, C and D in the following series of reactions.

Answer:

Question 33.
Write a short note on ortho – para directors aromat&c e1ropiJic substitution reactions.
Answer:
The group which increases the eleiron deity at oìo and para positions of the ring are known as ortho-para directors.
Example:
-OH, -NH₂ -NHR -CH₃, -OCH₃ etc.
Let us consider the directive influences of phenolic( -OH) group. Phenol is the resonace hybrid of following structure.

In these resonance structures the negative charge residue is present on ortho and para posrtions of the ring structure. Therefore the electron density at ortho and para positions increases as compared to the metci position, thus phenolic group activities the benzene ring for electrophilic attack at ortho and para positions and hetice – OH group is an ortho-para direction or and an activator.

Question 34.
How is propyne prepared from an alkyene dihalide?
Answer:

Question 35.
An alkyl halide with molecular formula C₆H₁₃Br on dehydrohalogenation gave two isomeric alkenes X and Y with molecular formula C₆H₁₂. On reductive ozonolysis, X and Y gave four compounds CH₃COCH₃. CH₃CHO, CH₃CH₂CHO and (CH₃)₂ CHCHO. Find the alkyl halide.
Answer:
1. C₆H₁₃Br is 3 – Bromo – 4 methylpentanc.

2. 3 – Bromo -4 methylpentane on dehydrogenation give two isomers X and Y as follows:

There fore C₆H₁₃ Br is 3 – Bromo – 4 – methy ipentane.

Question 36.
Describe the mechanism of Nitration of benzene.
Answer:
Step-1 :
Generation of \(\overset { \oplus }{ { NO }_{ 2 } } \) electrophile.
HNO₃ + H₂SO₄ → \(\overset { \oplus }{ { NO }_{ 2 } } \) + H\(\overset { \oplus }{ { SO }_{ 4 } } \) + H₂O

Step-2:
Attack of the electrophile on benzene ring to form arenium ion.

Step-3:
Rearomatisation of arenium ion.

Overall Reaction:

Question 37.
How does Huckel rule help to decide the aromatic character of a compound?
Answer:
A compound is said to be aromatic, if it obeys the following rules:

• The molecule must be cyclic.
• The molecule must be co-planar.
• Complete delocalisation of it-electrons in the ring.
• Presence of (4n + 2) π electrons in the ring where n is an integer (n = 0,1,2 …)

This is known as Huckel’s rule.
Example:

1. It is cyclic one.
2. It is a co-planar molecule.
3. It has six delocalised ir electrons.
4. 4n + 2 = 6
4n = 6 – 2
4n = 4
n = 1
It obey Huckel’s rule, with n = 1, hence benzene is aromatic in nature.

Question 38.
Suggest the route for the preparation of the following from benzene.
1. 3 – chioro – nitrobenzene
2. 4- chlorotoluene
3. Bromobenzene
4. in – dinitrobenzene
Answer:
1. Preparation of 3 – chloronitro – benzene from benzene:
Benzene undergoes nitration and followed by chlorination and it leads to the formation of 3- chloronitrobenzene.

2. Preparation 4-chiorotoluene from benzene:
Benzene undergoes Fnedel crafi’s alkylation followed by chlorination and it leads to the formation of 4-chiorotoluene.

3. Prepar2tion of Bromobenzene from benzene:
Bezene undergo bromination to give bromobenzene.

4. Preparation of m-dinitrobenzene from benzene:
Benzene undergo twice the time nitration to give m-dinitrobenzene.

Question 39.
Suggest a simple chemical test to distinguish propane and propene.
Answer:
Chemical test to distinguish between propane and propene:
1. Bromine water test:
Propene contains double bond, therefore when we pour the bromine water to propene sample, it decolounses the bromine water whereas propane which is a saturated hydrocarbon does not decolourise the bromine water.

2. Baeyer’s test:
When propene reacts with Bayer’s reagent it gives 1,2 dihydroxypropene. Propane does not react with Baeyer’s reagent.

Question 40.
What happens when isobutylene is treated with acidified potassium permanganate?
Answer:
Isobutylene is treated with acidified KMnO₄ to give acetone.

Question 41.
how will you convert ethyl chloride in to –
1. ethane
2. n – butane
Answer:
1. Conversion of ethyl chloride into ethane:

2. Conversion of ethyl chloride into n-butane:
Wurtz reaction:

Question 42.
Describe the conformers of n-butane.
Answer:
n-butane may be considered as a derivative of ethane as one hydrogen on each carbon atom is replaced by a methyl group.

Edipsed conformation:
In this conformation, the distance between the two methyl groups is minimum so there is maximum repulsion between them and it is the least stable conformer.

Anti or staggered form:
In this conformation, the distance between the two methyl groups is maximum and so there is minimum repulsion between them. It is the most stable conformer. The following potentially energy diagram shows the relative stability of various conformers of n-butane.

Question 43.
Write the chemical equations for combustion of propane.
Answer:
Chemical equations for combustion of propane:
The general combustion reaction for any alkane is:

Question 44.
Explain Markovnikoffs rule with suitable example.
Answer:
Markovnikoff’s rule: When an unsymmetrical alkene reacts with hydrogen halide, the hydrogen adds to the carbon atom that has more number of hydrogen and halogen adds to the carbon atom having fewer hydrogen atoms.
Example:
Addition of HBr to Propene:

Question 45.
What happens when ethylene is passed through cold dilute alkaline potassium permanganate.
Answer:
Ethylene reacts with cold dilute alkaline KMnO₄ solution to give ethylene glycol:

Question 46.
Write the structures of following alkanes.
1. 2, 3 – Dimethyl – 6 – (2 – methylpropyl) decane
2. 5 – (2 – Ethylbutyl) – 3, 3 – dimethyldecane
3. 5 (1,2 – Dimethyipropyl) – 2 – methylnonane
Answer:
1. 2, 3 – Dimethyl – 6 – (2 – rnethylpropyl) decane

2. 5 – (2 – Ethylbutyl) – 3, 3- dimethyldecane

3. 5 – (1,2 – Dimethylpropyl) – 2- methylnonane

Question 47.
How will you prepare propane from a sodium salt of fatty acid?
Answer:

Sodium salt of butyric acid on heating with sodalime gives propane.

Question 48.

Answer:

Question 49.
How will you distinguish 1 – butyne and 2 – butyne?
Answer:

Answer:

Question 50.
How will you distinguish 1 – butyene and 2 – butyne?
Answer:

In 1-butyne, terminal carbon atom contains atom one acidic hydrogen, therefore it will react with silver nitrate in the presence of ammonium hydroxide to give silver butynide. Whereas 2-butyne does not undergo such type of the reaction, because of the absence of acidic hydrogen.

Samacheer Kalvi 11th Chemistry Hydrocarbons Evaluate Your self

Question 1.
Write the structural formula and carbon skeleton formula for all possible chain isomers of C₆H₁₄ (Hexane).
Answer:
C₆H₁₄ has five possible isomeric structures:

Question 2.
Give the IUPAC name for the following alkane.


Answer:

Question 3.
Draw the structural formula for 4,5 -diethyl -3,4,5-trimethyloiane
Answer:

Question 4.
Water destroys Grignard reagents. Why?
Answer:
CH₃MgX + HOH → CH₄ – Mg(OH)X.
Water would protonate the grignard reagent and destroy the gngnard reagent, because the grignard carbon atom is highly nucleophilic. This would form a hydrocarbon. Therefore to make a grignard solution, only ether is the best solvent and water or alcohol are not used for that purpose.

Question 5.
Is it possible to prepare methane by Kolbe’s electrolytic method.
Answer:
Kolbe’s electrolytic method is suitable for the preparation of symmetrical alkanes, that is alkanes containing even number of carbon atoms. Methane has only one carbon, hence it cannot be prepared by Kolbe’s electrolytic method.

Question 6.
Write down the combustion reaction of propane whose AH° = -2220 kJ
Answer:

Question 7.
Why ethane is produced in chlorination of methane?
Answer:
Chlorination of methane involves free radical mechanism. During the propagation step methyl free radical is produced, which is involved in the termination step, the two methyl free radical then combines to form ethane.

Question 8.
How toluene can be prepared by this method?
(i) From n-heptane,
(ii) From 2-methyihexane
Answer:

(ii)

Question 9.
Write the IUPAC names for the following alkenes.

Answer:

Question 10.
Draw the structures for the following alkenes.

1. 6 – Bromo – 2,3 – dimethyl 2 – hexene
2. 5 – Bromo – 4 – chloro 1 – heptene
3. 2,5 – Dimethyl 4 – octene
4. 4 – Methyl – 2 pentene

Answer:
1. 6 – Bromo – 2,3 – dirnethyl – 2 – hexene:

2. 5 Bromo -4 – Chloro – 1 – heptene:

3. 2.5 – dimethyl – 4 – Octene:

4. 4 – methyl 2 pentene:

Question 11.
Draw the structure and write down the IUPAC name for the isomerism exhibited by the molecular formulae:
1. C₅H₁₀ – Pentene (3 isomers)
2. C₆H₁₂ – Hexene (5 isomers)
Answer:
1. C₅H₁₀ – Pentene (3 isomers)
(a) CH₃ – CH₂ – CH₂ – CH = CH₂ → 1- penlene (or) pent- 1-ene
(b) CH₃ – CH₂ – CH = CH – CH₃ → 2- pentene (or) pent-2-ene

2. C₆H₁₂ – Hexene (5 isomers)
(a) CH₃ – CH₂ – CH₂ – CH₂ – CH = CH₂ → Hex-I-ene
(b) CH₃ – CH₂ – CH₂ – CH = CH – CH₃ → Hex – 2 – ene
(c) CH₃ – CH₂ – CH = CH – CH₂ – CH₃ → Hex – 3 – ene


These two compounds exhibits constitutional isomerism.

Question 12.
Determine whether each of the following alkenes can exist as cis-trans isomers?
(a) 1 – Chloropropene
(b) 2 – Chloropropene
Answer:
(a) 1 – Chloropropene:
CH₃ – CH = CHCl

Therefore – 1 – Chloropropene has cis-trans isomers.

(b) 2 – Chloropropene:

In 2-Chloropropene, it deviates from the rule, that is “At least one same group is present on the two doubly bonded carbon atom”. Therefore-2-chloropropenc cannot exist as cis – trans isomers.

Question 13.
Draw cis-trans isomers for the following compounds
(a) 2- chloro-2-butene
(b) CH₃ – CH= CH – CH₂ – CH₃
Answer:
(a) 2-Chloro-2-butene:

(b) CH₃ – CH = CH – CH – CH₃

Question 14.
How propene is prepared form 1, 2-dichloropropane?
Answer:

Question 15.
How ozone reacts with 2-methyl propene?
Answer:

Question 16.
An organic compound (A) on ozonolysis gives only acetaldehyde. (A) reacts with Br₂ /CCl₄ to give compound (B). Identify the compounds (A) and (B). Write the IUPAC name of (A) and (B). Give the geometrical isomers of (A).
Answer:
2-Rutene undergo ozonolysis to give acetaldehyde only.


Geometrical isomers of 2 – Butene (A):

Question 17.
An organic compund (A) C₂H₄ decolourises bromine water. (A) on reaction with chlorine gives (Br). A reacts with HBr to give (C). Identify (A),(B),(C). Explain the reactions.
Answer:
(i) C₂H₄ (A), decolourises the bromine water. Therefore it contains double bond. Hence (A) is ethylene.

Question 18.
Prepare propyne from its corresponding alkene.
Answer:
Preparation of propyne from propene:

Question 19.
Write the products A & B for the following reaction.

Answer:

Question 20.

Answer:

Question 21.
Calculate the number of rings present in C₁₈H₁₂.
Answer:
Double bond equivalent formula = ( C – \(\frac {1}{2}\) + \(\frac {1}{2}\))
Where C = no. of carbon atoms. H = no. of hydrogen and halogen atoms and N = no. of nitrogen atoms.
So. in C₁₈H₁₂ Double bond equkalent = 18 – \(\frac {12}{2}\) + 0 + 1 = 18 – 6 + 1 = 13

One ring is equal to one double bond equivalent.
∴ here four rings are there, four double bond equivalent arc used. So remaining, 13 – 4 = 9.
nine double bonds are present in the ring. Hence, C₁₈H₁₂ contain four aromatic rings.

Question 22.
write all possible isomers for an aromatic benzenoid compound having the molecular formula C₈H₁₀.
Answer:
Possible isomers for C₈H₁₀:

Question 23.
Write all possible isomers Iòr a monosubstituted aromatic benzenoid compound having the molecular formula C₉H₁₂
Answer:
Possible isomers for C₉H₁₂:

Question 24.
how benzene can be prepared by Grignard Reagent?
Answer:
Phenyl magnesium bromde reagent reacts with water molecule to give benzene:

Question 25.
Why benzene undergoes electrophilic substitution reaction whereas alkenes undergoes addition reaction?
Answer:

• Benzene possess an unhybridised p-orbital containing one electron. The lateral overlap of theirp-orbitals produces 3 it bond.
• The six electron of the p-orbitais cover all the six carbon atoms and arc said to be delocalised.
• Due to delocalisation, strong it-bond is formed which makes the molecule stable. Therefore benzene undergoes electrophilic substitution reaction, whereas alkenes undergoes addition reaction.

Question 26.
Convert Ethyne to Benzene and name the process.
Answer:
Conversion of Ethyne into Benzene:

This process is one of the cyclic polymerisation process.

Question 27.
Toluene undergoes nitration easily than benzene.Why?
Answer:
1. Toluene has a methyl group on the benzene ring which is electron releasing group and hence activate the benzene ring by pushing the electrons on the benzene ring.
2. CH₃ group is ortho – para director and ring activator. Therefore in toluene, ortho and para positions are the most reactive towards an electrophile, thus promoting electrophilic substitution reaction.
3. The methyl group hence makes it around 25 times more reactive than benzene. Therefore it undergoes nitration easily than benzene.

Samacheer Kalvi 11th Chemistry Hydrocarbons Additional Questions Solved

Choose the correct statement.

Question 1.
Statement-I : Methane. ethane, propène and butane are alkane group compounds.
Statement-II : They are obeying C₂H_2n+2 + formula and each member differs from it proceeding member by a CH₂ group.
(a) Statement-I and II are correct and Statement-II is correct explanation of statement-I.
(b) Statement-I and II are correct but statement-II is not correct explanation of statement-I
(e) Statëment-I is correct but statement-II is wrong.
(d) Statement-I is wrong but statement-II is correct.
Answer:
(a) Statement-I and II are correct and Statement-II is correct explanation of statement-I.

Question 2.
Statement – I : n – butane and iso – butane are isomers.
Statement – II : Because they are having same molecular formula but differs only in the structural formula.
(a) Statement -I and II are correct and statement – II is correct explanation of statement – I
(h) Statement – I and II are correct but statement – II is not correct explanation of statement -I
(c) Statement – I is correct but statement – II s wrong.
(d) Statement – I is wrong but statement – II is correct.
Answer:
(a) Statement -I and II are correct and statement – II is correct explanation of statement-I

Question 3.
Which one of the following shows three possible isomeric structures’?
(a) C₄H₁₀
(b) C₅H₁₂
(c) C₆H₁₂
(d) C₃H₄
Answer:
(b) C₅H₁₂

Question 4.
Find out the branched hydrocarbon from the following compounds.
(a) 1 – propane
(b) n – propane
(c) iso – butane
(d) n – butane –
Answer:
(c) iso – butane

Question 5.
Which of the following compound cannot be prepared by Kolbe’s electrolytic method’?
(a) CH₃-CH₃
(b) CH₄
(c) CH₂ = CH₂
(d) CH = CH
Answer:
(b) CH₄

Question 6.
Statement – I : Boiling point of methane is lower than that of butane.
Statement – II : The boiling point of continuous chain alkanes increases with increase in length of carbon chain.
(a) Statement – I and II are correct and statement – II is correct explanation of statement – I
(b) Statement – I and II are correct but statement – II is not correct explanation of statement -I
(c) Statement – I is correct but statement – II is wrong.
(d) Statement – I is wrong but statement – I is correct.
Answer:
(a) Statement – I and II are correct and statement – II is correct explanation of statement -I.

Question 7.
Statement – I : Alkenes shows both structural and geometrical isomerism.
Statement – II : Because of the presence of double bond.
(a) Statement – I and II are correct and statement-II is correct explanation of statement – I.
(b) Statement – I and II are correct but statement-II is not correct explanation of statement – I
(c) Statement – I is correct but statement – II is wrong.
(d) Statement – II is wrong but statement – II is correct.
Answer:
(a) Statement – I and II are correct and statement – II is correct explanation of statement – I.

Question 8.
Consider the following statements.
(i) The process of reduction using sodium in liquid ammonia is called as Birch reduction.
(ii) Birch reduction is stereospecific in reaction.
(iii) Aleynes can be reduced to cis – alkenes using Birch reduction. Which of the above statement is/are correct’?
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) only
(d) (ii) only
Answer:
(a) (i) and (ii)

Question 9.
Statement – I : Alkenes are more reactive than alkanes.
Statement – II : Because of the presence of a double bond.
(a) Statement – I and II are correct and statement – II is correct explanation of statement – I
(b) Statement – I and Il are correct but statement – II is not correct explanation of statement -I
(c) Statement – I is correct but statement – II is wrong.
(d) Statement – I is wrong but statement – II is correct.
Answer:
(a) Statement – I and II are correct and statement – II is correct explanation of statement – I

Question 10.
Peroxide effect is not observed in ………..
(a) HCl
(b) HI
(c) HBr
(d) Both (a) and (b)
Answer:
(d) Both (a) and (b)

Question 11.
Which one of the following has garlie odour?
(a) Ethane
(b) Ethene
(c) Ethyne
(d) Ethanol
Answer:
(c) Ethyne

Question 12.
Identify the X.
(a) Propane
(b) Acetone
(c) Acetaldehyde
(d) Formaldehyde
Answer:
(b) Acetone

Question 13.
Which one of the following is not a monocyclic aromatic hydrocarbon?
(a) Benzene
(b) Phenol
(c) Toluene
(d) Naphthalene
Answer:
(d) Naphthalene

Question 14.
Which one of the following is a polynuclear aromatic hydrocarbon?
(a) Anthracene
(b) Phenol
(c) Benzene
(d) Toluene
Answer:
(a) Anthracene

Question 15.
Which one of the following is an aromatic compounds?

Answer:

Question 16.
Molecular formula of benzene is ………….
(a) C₆H₆
(b) C₆H₅
(c) C₇H₈
(d) CH₄
Answer:
(a) C₆H₆

Question 17.
Statements-I : Unlike alkenes and alkynes benzene undergoes substitution reactions rather than addition reaction under normal conditions.
Statements-II : Because of the delocalisation of electrons a strong t bond is formed which makes the molecule stable.
(a) Statement-I and II are correct and statement-II is correct explanation of statement-I.
(b) Statement-I and II are correct but statement-II is not correct explanation of statement-I
(c) Statement-I ¡s correct but statement-II is wrong.
(d) Statement-I is wrong but statement-II is correct.
Answer:
(a) Statement-I and II are correct and statement-II ls correct explanation of statemen-I.

Question 18.
A → B + H₂O. Identify A and B.

Answer:

Question 19.
Benzene undergoes Birch reduction to form .

Answer:

Question 20.
Which one of the following is not an ortho-para director?
(a) – NO₂
(b) – CH₃
(c) – OH
(d) – C₂H₅
Answer:
(a) – NO₂

Question 21.
Which one of the following is not a meta director’?
(a) – NH₂
(b) – NO₂
(c) – COOR
(d) – SO₃H
Answer:
(a) – NH₂

Question 22.
Which one of the following benzene ring deactivator?
(a) – CHO
(b) – OH
(c) – CH₃
(d) – OCH₃
Answer:
(a) – CHO

Question 23.
Fine the odd one out:
(a) Benzene
(b) Ethane
(c) Ethene
(d) Propyne
Answer:
(a) Benzene

Question 24.
Which among these is not associated with atiphatic compounds?
(a) They contain (4n+2) π electrons
(b) They contain straight chain compounds.
(c) They contain branched chain compounds.
(d) They have appropriate number of H-atoms and functional groups.
Answer:
(a) They contain (4n+2) π electron.

Question 25.
Which of the following compounds will exhibit cis-trans isomerism
(a) 2 – Butene
(b) 2 – Butyne
(c) 1 – Butene
(d) 2 – Butanol
Answer:
(a) 2 – Butene

Question 26.
Which conformation of ethane has the lowest potential energy?
(a) Eclipsed
(b) Staggered
(c) Skew
(d) All will have equal potential energy.
Answer:
(b) Staggered

Question 27.
Which of the following is less reactive than benzene towards electrophilic substitution reactions?
(a) Nitrobenzene
(b) Aniline
(c) Bromobenzene
(d) Chlorobenzene
Answer:
(a) Nitrobenzene

II. Match the following
Question 1.


Answer:

Question 2.

Answer:

Question 3.


Answer:

Question 4.


Answer:

Question 5.


Answer:

Question 6.


Answer:

Question 7.

Answer:

Question 8.


Answer:

III. Fill in the blanks.

Question 1.
Liquefied petroleum gas consist of a mixture of ………..
Answer:
Propane + butane

Question 2.
Mangoes contain ………….
Answer:
Cyclo hexane

Question 3.
Methane gas is also called as ………….
Answer:
Marsh gas

Question 4.
The IUPAC name of the following compound is:

Answer:
3-Ethyl, 2-methylpentane

Question 5.
Sodalime is the mixture of ……………
Answer;
NaOH + CaO

Question 6.
Wurtz reaction used in the preparation of …………
Answer:
higher alkanes

Question 7.
The major reagent present in Corey-House reaction is ………..
Answer:
Lithium dimethyl cuparate

Question 8.
General formula for grignard reagents is ………..
Answer:
R – MgX

Question 9.
The rotation of C – C single bond leads to different isomenc structure called as …………
Answer:
conformers

Question 10.
The least stable conformer of ethane is form ……….
Answer:
eclipsed

Question 11.
The potential energy difference between the staggered and eclipsed conformation of ethane is …………
Answer:
12.5 kJ /mol

Question 12.
The most stable conformer of butane is ………..
Answer:
Staggered

Question 13.
Paraffin is the older name for the group family of compounds.
Answer:
alkane

Question 14.
Paraffin means ……….
Answer:
Little activity

Question 15.
Preparation of methyl chloride is followed by mechanism.
Answer:
Free radical

Question 16.
n – hexane passed over chromic oxide supported on alumina at 873 K will give ……….
Answer:
Bcnzene

Question 17.
The number of possible isomers of C₆H₁₂ is …………..
Answer:
5

Question 18.
When ethanol is heated at 440 K with excess of concentrated H2SO4, it will give …………
Answer:
Ethene

Question 19.
Alkynes undergoes reduction using Lindlar’s catalyst to give ………….
Answer:
cix – alkenes

Question 20.
Alkynes undergoes reduction using sodium in liquid ammonia to give …………
Answer:
trans – alkenes

Question 21.
Aqueous solution of potassium succinate is electrolysed to give ………….
Answer:
Ethane

Question 22.
The order of reactivity of different hydrogen halides (HCl, HI , HBr) is ………..
Answer:
HI >HBr >HCl

Question 23.
Addition of hydrohalides to alkene is an example for …………
Answer:
Electrophilic additton

Question 24.
Ethane reacts with HBr to form …………
Answer:
Bromo ethane

Question 25.
Homolytic fission of benzoyl peroxide will give ………..
Answer:
C₆H₅

Question 26.
Propene reacts with HBr in the presence of peroxide to form …………
Answer:
1 – Bromopropane

Question 27.
Baeyer’s reagent is …………
Answer:
alkaline KMNO₄

Question 28.
Ozonolysis of ethene produces ………….
Answer:
HCHO

Question 29.
Electrolysis of potassium maleate yields ………
Answer:
Ethyne

Question 30.
Ozonolysis of acetylene gives ………….
Answer:
HCOOH

Question 31.
Three molecules of acetylene undergoes polymerisation to give …………
Answer:
benzene

Question 32.
Benzene reacts with bromine in the presence of AlCl₃ to form bromobenzene and it is an example of reaction
Answer:
Electrophilic substitution

Question 33.
The six carbon atoms of benzene are hybridised.
Answer:
sp²

Question 34.
Bond angle in benzene is …………
Answer:
120º

Question 35.
Benzene contains a bonds and it bonds …………
Answer:
12,3

Question 36.
Wurtz-fittig reaction helps to prepare compounds …………
Answer:
aromatic

Question 37.
When phenol reacts with Zn-dust under dry distillation conditions it gives ………..
Answer:
Benzene

Question 38.
Benzene is insoluble in …………
Answer:
water

Question 39.
Benzene reacts with hydrogen in the presence of Pt to yield ……….
Answer:
Cyclohexane

Question 40.
Benzene reacts with Cl₂ in the presence of sunlight to give ………..
Answer:
BHC (Ben.zene hexachioride)

Question 41.
The step in which Cl-Cl bond homolysis occurs is called ……….
Answer:
Initiation step

Question 42.
Dienes are the name given to compounds with ……….
Answer:
Exactly two double bonds

Question 43.
The hybridisation state of a carbocation is …………
Answer:
sp²

Question 44.
The peroxide effect in anti-markovnikoff addition involves a ………. mechanism.
Answer:
free radical.

IV Choose the odd one out
Question 1.
(a) Ethane
(b) Benzene
(c) Ethene
(d) Ethyne
Answer:
(b) Benzene. it is an aromatic hydrocarbon whereas others are aliphatic hydrocarbons.

Question 2.
(a) Zn + HCl
(b) Zn + CH₃COOH
(c) LiAlH₄
(d) Acidified K₂Cr₂O₇
Answer:
Acidified K₂Cr₂O₇. It is an oxidising agent whereas other three reagents are reducing

Question 3.
(a) Soft drink bottle
(b) Jars
(c) Vegetable oil bottle
(d) Straws
Answer:
(d) Straws. It is made up of polypropylene whereas others are made of PET (Polyethylene terephthalate).

Question 4.
(a) Straws
(b) Foam cups
(c) Diapers
(d) Toys
Answer:
(b) Foam cups. It is made up of polystyrene whereas others are made up of polypropylene.

Question 5.
(a) Orlon
(b) Neoprene rubber
(c) PVC
(d) PET
Answer:
(d) PET. It is prepared by the polymerisation of glycol and terephthalic acid, whereas others are prepared from acetylene.

Choose the correct pair.

Question 1.
(a) Propene + O₃ : HCHO + CH₃ CH0
(b) Ethene + O₃ : CH₃ CHO + H₂O₂
(c) But-2-ene + O₃ : HCHO + H₂ O₂

Answer:
(a) Propene + O₃ : HCHO + CH3CHO

Question 2.
(a) PET : shampoo bottles
(b) PS : disposable utensils
(c) PP : grocery bags
(d) HDPE : plastic pipes
Answer:
(b) PS : disposable utensils

Question 3.

Answer:

Question 4.

Answer:

VI. Choose the incorrect pair.

Question 1.

Answer:

Question 2.
(a) CH₂ = CH₂ + O₃ : 2HCOH
(b) CH₃ – CH = CH₂ + O₃ : CH₃CHO + HCHO
(c) CH₃ – CH = CH – CH₃ + O₃ : 2CH₃COCH₃
(d) CH₃ – CH = CH – CH₃ + O₃ : 2CH₃CHO
Answer:
(c) CH₃ – CH = CH – CH₃ + O₃ : 2CH₃COCH₃

Question 3.
(a) PET : Jars
(b) HDPE : Juice containers
(c) PS : Disposable utensils
(d) PVC : Grocery bags
Answer:
(d) PVC : Grocery bags

VII. Assertion & Reason.
Question 1.
Assertion (A) : Methane is called marsh gas.
Reason (R) : Decomposition of plant and animal matter in am oxygen deficient environment like swamps, mashes and bogs produce methane gas.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 2.
Assertion (A) : Water destroys grignard reagent and so it is not used as solvent for RMgX.
Reason (R) : Water decomposes grignard reagent (RMgX) to give alkane.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 3.
Assertion (A) : The boiling point of straight chain isomers have higher boiling point as compared to branched chain isomers.
Reason (R) : The boiling point decreases with increase in branching as the molecule becomes compact and the area of contact decreases.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A)is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 4.
Assertion (A) : The eclipsed conformation ofethane is less stable than staggered conformation of ethane.
Reason (R) : In eclipsed conformation, the distance between the two methyl group is minimum and so there is maximum repulsion between them and it is the least stable conformer.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A)and (R) are correct hut (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).

Samacheer Kalvi 11th Chemistry Hydrocarbons 2 Mark Questions and Answers

Question 1.
What are unsaturated hydrocarbons?
Answer:
hydrocarbons having localised carbon – carbon multiple bonds are called unsaturated hydrocarbons.
Example :
alkenes and alkynes.

Question 2.
What is marsh gas?
Answer:
Answer:

• Methane is the major component of the atmosphere of jupiter, Saturn, Uranus and Neptune but only minor component of earth atmosphere.
• Decomposition of plant and animal matter in an oxygen deficient environment like swamps, marshes bogs and the sediments of lakes produces methane gas. It is otherwise known as marsh gas.

Question 3.
Write a note on methane clathrates.
Answer:

• Frozen mixture of water and methane gas is chemically known as methane clathrate.
• The methane molecule which is produced by biological process under the deep -ocean (at 4°C and 50 atm) does not simply reach the surface instead each molecule is trapped inside the clusters of 6 to 18 water molecules forming methane clathratcs.

Question 4.
What is isomerism? Mention the types of isomerism?
Answer:
The phenomenon in which the same molecular formula may exhibit different structural arrangement is called isomerism.
There are two types of isomerism. namely.

• Structural isomerism
• Stereoisomerism

Question 5.
Draw and name the possible structural formula for C₄H₁₀
Answer:
C₄H₁₀ has two possible structural formula, they are,
(i) CH₃-CH₂-CH₂-CH₃ n-Butane

Question 6.
Give the IUPAC name of the following compounds.

Answer:

Question 7.
What is Sabatier- Sendersens reaction?
Answer:
The process of addition of H₂ to unsaturated compounds (alkenes or alkynes) in known as hydrogenation. The above process can be catalysed by nickel at 298 K. This reaction is known as Sabalier-Sendersens reaction.
For example:

Question 8.
What are decarboxylation reactions? Given an example.
Answer:
When a mixture of sodium salt of carboxylic acid and sodalime is heated an alkane is formed. During this process CO₂ molecule is eliminated process and this process is known as decarboxylation reaction.

Question 9.
Write a note on Kolbe’s electrolytic method?
Answer:
When potassium or sodium salt of carboxylic acid is electrolysed, a higher alkane is formed.

Question 10.
How will you prepare propane from Chloropropane?
Answer:
Nascent hydrogen reacts with chloropropane to give propane.

Question 11.
What is Wurtz reaction?
Answer:
When a solution of haloalkanc in dry ether is treated with sodium metal, higher alkanes are produced. This reaction is known as Wurtz reaction. For example:

Question 12.
Write shnrt flotes on Corey-House reaction?
Answer:
An alkyl halide and lithium dialkyl cupratc are reacted to give higher alkanes. This reaction is known as Corey-House reaction.

Question 13.
How will you prepare methane from grignard reagent’?
Answer:
Methyl magnesium chloride reacts with water to give methane.

Question 14.
What are conformers?
Answer:
The rotation about C-C single bond axis yielding several arrangements of a hydrocarbon called conformers.

Question 15.
Draw the conformations of ethane using Newman projection formula method?
Answer:

Question 16.
What are combustion reactions?
Answer:
A combustion reaction is a chemical reaction between a substance and oxygen with evolution of heat and light. In the presence of sufficient oxygen alkanes undergoes combustion when ignited and produces carbon dioxide and water.

Question 17.
What is arornatisation?
Answer:
Alkanes with six to ten carbon atoms are converted into homologous of benzene at higher temperature and in the presence of a catalyst. This process is known as aromatisation. For example, n-Hexane passed over Cr₂O₃ supported on alumina at 873 K gives benzene.

Question 18.
Write notes on isomerisation.
Answer:
1. Isomerisation is a chemical process by which a compound is transformed into any of its isomeric form.
2. Normal alkanes can be converted into branched alkanes in the presence ofAlCl₃ and HCl at 298 K.

3.  This process is of great industrial importance, the quantity of gasoline is improved by isomerising its components.

Question 19.
Mention the uses of alkanes.
Answer:

• Alkanes are extensively used as fuels.
• Methane present in natural gas is used in home heating.
• A mixture of propane and butane is known as LPG gas which is used for domestic cooking purpose.
• Gasoline is a complex mixture of many hydrocarbons used as a fuel for internal combustion engines.

Question 20.
Draw and name the structural formula for C4H8’?
Answer:
(i) CH₃ – CH = CH – CH₃ -w 1 – Butene
(ii) CH₂ = CH – CH₂ – CH₂ – 2 Butene

Question 21.
cis-isomers are less stable than rans-isomers?
Answer:
Consider:

Among cis and trans isomers, cis isomer is less stable than trans isomer. In the cis isomer, similar groups arc very near to each other. vander Waal’s repulsion and steric hindrance make the molecule much more unstable. But in trans isomer, similar groups are diagonally opposite to each other and there is no such steric hindrance. Due to more steric interaction cis isomers is less stable than Irons isomer.

Question 22.
How will you prepare ethene from ethanol?
Answrer:
When ethanol is heated at 430 K – 440 K with excess cone. H₂SO₄. a molecule of water from alcohol is removed and ethene or ethylene is formed.

Question 23.
How will you convert 1-brornopropane into popene?
Answer:

1-bromopropane reacts with alcoholic KOH and eliminate hydrogen bromide resulting in the formation of propene.

Question 24.
How will you prepare ethene by Kolbe’s electrolytic method?
Answer:
When an aqueous solution of potassium succinate is electrolysed between two platinum electrodes, ethene is produced at the anode.

Question 25.
Write any two test for alkenes.
Answer:

• Rapid decolourisation of bromine in CCl₄ without evolution of hydrogen bromide.
• Decolourisation of cold dilute aqueous solution of KMnO₄

Question 26.
State Markovnikoff’s rule.
Answer:
When an unsymmetrical alkene reacts with hydrogen halide, the hydrogen atom adds to the carbon atom that has more number of hydrogen atoms and halogen add to the carbon atom having fewer hydrogen atoms.

Question 27.
What is peroxide effect?
Answer:
The addition of HBr to an alkene in the presence of organic peroxide gives the antì-Markovnikofl’s product. This effect is called as peroxide effect.

Question 28.
Identify the products A and B from the following reaction.

Answer:

Question 29.
What happens when propcne reacts with concentrated H,S04?
Answer:
Propene reacts rjth cone. H2S04 to form 2 – propyl hydrogen sulphate in accordance with Markovnikoffs rule Further hydrolysis yields 2-propanol.

Question 30.
Complete the following reaction and identify A, B and C.

Answer:

Question 31.
Mention the uses of alkenes.
Answer:

• Alkenes are used as starting material in the synthesis of alcohols, plastics, detergents and fuels.
• Ethenc is the most important organic fcedstock in the polymer industry. Examples are, PVC, Sarans and Polythene. These polymers are used in the manufacture of floor tiles, shoe-soles, synthetic fibres, raincoats, pipes etc.

Question 32.
What are gem dihalides? How will you prepare propyne from gem dihalides?
Answer:
Compounds containing two halogen atoms on the same carbon atom are called gem dihalides. On heating 1,1 -dichloropropane with alcoholic KOH, it will give propyne.

Question 33.
How will you prepare acetylene from potassium maleate?
Answer:
Electrolysis of potassium maleate yields acetylene. This is one of Kolbe’s electrolytic reaction.

Question 34.
How will you prepare acetylene from calcium carbide?
Answer:
Acetylene can be manufactured in large scale by action of calcium carbide with water.

Question 35.
How will you convert ethyne into ethanol?
Answer:
Ethyne undergo hydration on warming with mercuric sulphate and dil H₂SO₄ at 333 K to form ethanol (Acetaldehyde).

Question 36.
Mention the uses of Acetylene.
Answer:

• Acetylene is used in oxy acetylene torch used for welding and cutting metals.
• It is used for manufacture of PVC, polyvinyl acetate, Polyvinyl ether, orlon and neoprene rubbers.

Question 37.
What are all the conditions for aromaticity?
Answer:
Huckel proposed that aromaticity is a function of electronic structure of an organic compound.
A compound may be aromatic, if it obey the following rules:

• The molecule must have a cyclic structure.
• The molecule must be co-planar.
• Complete delocalisation of it electrons in the ring.
• Presence of (4n + 2) it electrons in the ring where n is an integer (n = 0,1,2….), this is known as Huckel’s rule.

Question 38.
Classify the following compounds by using aromaticity concepts:

Answer:

• It is co-planar molecule.
•  It has six delocalised ir electrons.
•  4n + 26
  4n = 6 – 2
  4,n = 4
  n = 1, obeys Huckel’s rule with n = 1

(b) Cyclo-octatetraene.

1. Molecule is non-planar.
Hence it is a non-aromatic compound.

(c) Cyclopropyl cation.

• It has a co-planar structure.
• It has two delocalised it electrons.
  4n + 2 = 2
  4n = 0
  n = 0

Hence is an aromatic compound.

Question 39.
Write notes on Resonance of benzene?
Answer:
1. The phenomenon in which two or more structures can be written for a substance which has identical position of atoms is called resonance.
2. The actual structure of the molecule is said to be a resonance hybrid of the various possible alternative structures.

3.  In benzene, Kekule’s structures I and II represented the resonance structures, and structure III is the resonance hybrid of structures I and II.
4. The structures I and II exist only in theory. The actual structure of benzene is the hybrid of two hypothetical resonance structures.

Question 40.
How will you convert phenol into benzene?
Answer:
When phenol vapours are passed over zinc dust then it is reduced to benzene:

Question 41.
What is Wurtz-fitting reaction?
Answer:
When a solution of bromobenzene and iodomethane in dry ether is treated with metallic sodium, toluene is formed.

Question 42.
What are activating and deactivating groups?
Answer:

• When mono substituted benzene undergoes an electrophilic substitution reaction, the rate of the reaction and the site of attack of the incoming electrophile depends on the functional group already attached to it.
•  Some groups increases the reactivity of benzene ring and are known as activating groups.
• Some groups decreases the reactivity of benzene ring and are known as de-activating groups.
• Example:
  Activating groups: – NH₂ – OH. – CH₃ etc.
  Deactivating groups: – NO₃. CN, – CHO etc,

Question 43.
Why does benzcnc undergo clectrophilic substitution reactions easily and nucleophilic substitution with difficulty?
Answer:
Due to the presence of an electron cloud containing 6π – electrons above and below the plane of the ring, benzene is a rich source of electrons, Consequently, it attracts the electrophilic reagents towards it and repels the nucleophilic reagents. As a result, benzene undergoes electrophilic substitution reactions easily and nucleophilic substitution with difficulty.

Question 44.
Out of benzene, m – dinitrobenzene and toluene which will undergo nitration most easily and why?
Answer:
CH₃ group is an electron-donating group, while -NO₂ group is electron withdrawing group. Therefore, maximum electron density will be there in toluene, followed by benzene and it is least in pn-dinitrobenzene. Therefore, the ease of nitration decreases in the order:
Toluene > benzene > m – dinitrobenzene.

Question 45.
Why are alkanes called paraffins?
Answer:
Paraffins means little affinity. Alkanes due to strong C-C and C-H bonds are relatively chemically inert. They are thus called as paraflins.

Samacheer Kalvi 11th Chemistry Hydrocarbons 3 Mark Questions and Answers

Question 1.
Explain the classification of hydrocarbons.
Answer:

Question 2.
How to write the possible isomers of C₅H₁₂?
Answer:
1. To begin draw the carbon backbone of the straight chain isomer.
C-C-C-C-C

2. To determine the carbon backbone structure of the other isomers, arrange the carbon atoms in the other way:

3. Fill in ail the hydrogen atoms so that each carbon forms four bonds,

Question 3.
Explain how to draw the structural formula for 3-ethyl, 2, 3-dimethylpentane.
Answer:
3-ethyl, 2, 3-dimethylpentane.
Step 1:
The parent hydrocarbon is pentane. Draw the chain of five carbon atoms and number

Step 2:
Complete the carbon skeleton by attaching the alkyl group as they are specified in the name. An ethyl group is attached to carbon atom 3 and two methyl groups are attached to carbon atoms 2 and 3.

Step 3:
Add hydrogen atoms to the carbon skeleton so that each carbon atoms have four bonds.

Question 4.
In alkane compounds with same number of carbon atoms, straight chain isomers have higher boiling point as compared to branched chain isomers-justify statement.
Answer:

• The boiling point of continuous chain alkanes increases with increase in the length of carbon chain roughly about 30°C for every added carbon atom to the chain.
• Alkanes are non-polar compounds and having weak Vander Wal’s force which depends upon molecular surface area and hence increases with increase in molecular size.
• The boiling point decreases with increase in branching on the molecule i.e. as it becomes compact and the area of the contract decreases. Hence in alkanes with same number of carbon atoms, straight chain isomers have higher boiling point as compared to branched chain isomers.

Question 5.
Why oil spills in aqueous environment spread so quickly?
Answer:

• Water molecules are polar and akanes are non-polar. The insolubility of alkanes in water makes them a good water repellent for metals which protects the metal surface from corrosion.
• Because of their lower density than water they tòrm two layers and occupies the top layer. The density difference between alkanes and water explains why oil spills in aqueous environment spread so quickly.

Question 6.
Explain pyrolysis method.
Answer:
1. Pyrolysis is defined as the thermal decomposition of an organic compound into smaller fragments in the absence of air through the application of heat. Pyrolysis of alkanes is also named as cracking.

2. In the absence of air, whai alkane are vapours passed through red-hot metal it breaks into simpler hydrocarbons.

3. The product depends upon the nature of alkane, temperature, pressure and presence or absence of the catalyst.

Question 7.
Write notes on Geometrical isomerism or cis-trans isomerism.
Answer:
1. It is a type of stereoisomerism and it is also called cis-trans isomerism. Such type of isomerism results due to the restricted rotation of doubly bounded carbon atoms.

2. If the similar groups lie on the same side then the geometrical isomers are called as cis-is omers.

3. If the similar groups lie on the opposite side then the geometrical isomers are called as trans-isomers.

Question 8.
Explain how 2-butyne reacts with (a) Lindlar’s catalyst and (b) Sodium in liquid ammonia?
Answer:
(a) 2-butyne reacts with Lindlar’s catalyst:
2-butyne can be reduced to cis-2 butene using CaCO₃ supported in Pd -metal partially deactivated with sulphur.
This reaction is stereo specific giving only the cis-2-butene.

(b) 2-butyne reacts with sodium in liquid ammonia:
2-butyne can also be reduced to trans-2-butene using sodium in liquid ammonia. This reaction is stereospecific giving only the trans-2-butene.

Question 9.
What are vicinal dihalides? How will you prepane alkene from vicinal dihaldes?
Answer:
1. The compounds in which two halogen atoms are attached to adjacent carbon-atoms are called as vicinal dihalides.

2. When vicinal dihalides are warmed with granulated zinc in methanol they lose a molecule

Question 10.
Why alkenes are more reactive than alkanes?
Answer:
1. Alkenes are more reactive than alkanes due to the presence of a double bond.

2. The a-bond is strong but the it-bond is weak. The typical reactions of alkenes involve the addition of an electrophile across the double bond proceeding through ionic mechanism. However addition reactions proceed through free-radical mechanism also. Ozonolysis and nolvmerisation are some of the characteristic reaction of alkenes.

Question 11.
Explain the mechanism of addition of HBr to propenc.
Answer:
Step 1:
Formation of electrophile:
In HBr, br is more electronegative than H. When bonded electron move towards Br, polarity is deve[oped and it creates electrophile H⁺ which attacks to the double bond to form a carbocation.

Step 2 :
Secondary carbocation is more stable than primary carhocation and it predominates over the primary carbocation.

Step 3 :
The Br^-1 ion attack the 2°- carbocation to form 2-Bromo propane as the major product.

Question 12.
Explain the mechanism of addition of FlBr to 3-methyl-1-butene.
Answer:
Consider the addition of HBr to 3-methyl-1-butene. Here the expected product according to Markovnikoff’s rule is 2-bromo-3-methylbutane but the actual major product is 2-bromo- 2-methylbutane. This is because, the secondary carbocation formed during the reaction is rearranged to give the more stable tertiary carbocation. Attack of Br^-1 on this tertiary carbocation gives the major product 2-bromo-2-methylbutane

Question 13.
Why peroxide effect is not observed in HCl and HI?
Answer:
The H-Cl bond is stronger (430.5 k.J mol^-1) than H-Hr bond (363.7 kJ mol^-1), thus H-Cl is not cleaved by the free radical. The H-I bond is further weaker (296.8 kJ mol^-3) than H-Cl bond. Thus H-I bond breaks easily hut iodine free radicals combine to form iodine molecules instead of adding to the double bond and hence peroxide effect is not observed in case of HCl and HI.

Question 14.
Explain the ozonolysis of (a) Ethene and (b) propene
Answer:
Ozonolysis is a method ofoxidative cleavage of alkenes using ozone and it form two carbonyl compounds. Alkenes react with ozone to form ozonide and it is cleaved by Zn/H₂O to form smaller molecules.
This reaction is often used to identify the structure of unknown alkene by detecting the position of double or triple bond.

Question 15.
What is polymerisation? Explain with suitable example.
Answer:
A polymer is a large molecule formed by the combination of large number of small molecules (monomers). This process is known as polymerisation. A few examples are:

Question 16.
Complete the following reactions:

Answer:

Question 17.
Explain the ozonolysis of (a) Acetylene (b) Propyne
Answer:
Ozone adds to carbon-carbon triple bond of alkynes to form ozonides. The ozonides are hydrolysed by water to form carbonyl compounds. The hydrogen peroxide formed in the reaction may oxidise the carbonyl compound to carboxylic acid.
(a) Acetylene:

(b) propyne:

Question 18.
Explain the polyrnerisation of acetylene molecules.
Answer:
Acetylene undergoes two types of polymerisation reactions, they are:

1. Linear polymerisation
2. Cyclic polymerisation

1. Linear polymerisation:
Acetylene forms linear polymer, when passed into a solution of cuprous chloride and ammonium chloride.

2. Cyclic polymerisation:
Acetylene undergoes cyclic polymerisation on passing through red hot iron tube. Three molecules of acetylene polymerises to form benzene.

Question 19.
Discuss the Kekule’s structure of benzene.
Answer:
Kekule suggested that benzene consists of a cyclic planar structure of six carbon with alternate single and double bonds.
There were two objections:
1. Bnzene forms only one ortho disubstituted products whereas the Kekule’s structure predicts two ortho disubstituted products as shown:

2. Kekule’s structure failed to explain why benzene with three double bonds did not give addition reaction like alkenes. To overcome this objection, Kekule suggested that henzene was a resonance hybrid of two forms(1 and 2) which are in rapid equilibrium.

Question 20.
Why benzene undergoes substitution reaction rather than addition reactions under normal conditions?
Answer:
1. Each carbon atom in henzene possess an unhybridised p-orbital containing one electron. The lateral overlap of their p-orbitais produces 3π- bond, six electrons of the p-orbitais over all the six carbon atoms and are said lo be delocalised.

2. Due to delocalisation, strong it-bond is formed which makes the molecule stable. Hence unlike alkenes and alkynes, benzene undergoes substitution reactions rather than addition reactions under normal conditions.

Question 21.
Explain the industrial preparation of benzene from coal tar.
Answer:
Coal tar is a viscous liquid obtained by the pyrolysis of coal. During fractional distillation, coal tar is heated and distills away its volatile compounds, namely, benzene, toluene, xylene in the temperature range of 350 K to 443 K. These vapours are collected at the upper part of the fractionating column.

Question 22.
Explain the suiphonation of benzene.
Answer:
Benzcne reacts with fuming sulphuric acid and give benzene suiphonic acid. Although SO₃ molecule it does not have positive charge, yet it is a strong electrophile. This is because the octet of electrons around the sulphur atom is not reacted. This reached is reversible nd desulphonation occus readily in aqueous medium.

Question 23.
What is BHC? How will you prepare BHC? Mention its uses.
Answer:
1. BHC is I3enzene hexachioride.
2. Benzene reacts with three molecule of Cl₂in the presence of sunlight or UV light to yield BHC.
This is also called as gammaxane or Lindane.

3. BHC is a powerful insecticide.

Question 24.
In aryl halides, halogen group is a oriho -para director and a deactivator towards electrophilic substitution reactions, why?
Answer:
1.  In aryl halides, the strong -I effect of the halogens decreases the electron density of benzene ring, thereby deactivating it for electrophilic attack.
2. The presence of lone pair on halogens is involved in resonance with π-electrons of the benzene ring and it increases the electron density at ortho and para position. Hence the halogen group is an ortho-para director and a deactivator.

Question 25.
Explain the carcinogenity and toxicity of aromatic hydrocarbons.
Answer:
Benzene and polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants generated during incomplete combustion of coal, oil, petrol and wood. Some (PAH) originate from open burning, natural seepage of petroleum and coal deposits and volcanic activities. They are toxic, mutagenic and carcinogenic. It has hematological, immunological and neutrological effect on humans They are radioactive and prolonged exposure leads to genetic damage. Some of the examples of PAH arc “L” shaped polynuclear hydrocarbons, which are much more toxic and carcinogenic.

It is found in cigarette smoke, in tobacco and and charcoal boiled food.

It is found in gasoline exhaust and barbecued food.

Question 26.
Arrange benzene, n-hexane and ethyne in decreasing order of acidic behavior. Also give reason for this behavior?
Answer:

Since s-electrons arc closer to the nucleus, therefore as the s-character of the orbital making the C-H bond increases the electrons of C-H bond lies closer and closer to the carbon atom. In other words, the partial +ve charge on the H-atom and hence the acidic character increases as the s-character of the orbital increases. Thus, the acidic character decreases in the order
Ethyne > Benzene > Hexane

Samacheer Kalvi 11th Chemistry Hydrocarbons 5 Mark Questions

Question 1.
Explain the conformational analysis of ethane.
Answer:
The two tetrahedral methyl groups can rotate about the carbon-carbon bond axis yielding several arrangements called conformers. The extreme conformations are staggered and eclipsed conformations. There can be number of other arrangements between staggered and eclipsed forms and their arrangements are known as skew forms.

Eclipsed conformation:

In this conformation, the hydrogen of one carbon atom is directly behind those of the other. The repulsion between the atoms is maximum and it is the least stable conformer.

Staggered conformation:

In this conformation, the hydrogen’s of both the carbon atoms are tir apart from each other. The repulsion between the atoms is minimum and it is the most stable conformer.

Skew formation:
The infinite numbers of possible intermediate conformations between the two extreme conformations are referred as skew conformations. The stabilities of various conformations of ethane are
Staggered > Skew> Eclipsed
The potential energy difference between the staggered and eclipsed conformation of ethanc is around 12.5 kJ mol^-1HBr The various conformations can be represented by Newman projection formula.

Newman Projection formula for Ethane:

Question 2.
Explain the structure of benzene.
Answer:
1. Molecular formula:
Elemental analysis and molecular weight determination have proved that the molecular formula of benzene is C₆H₆. This indicates that benzene is a highly unsaturated compound.

2. Straight chain structure is not possible:
Benzene could be constructed as a straight chain but it not feasible since it does not show the properties of alkenes or alkynes. For example, it does not decolorise the bromine water in CCl₄.

3. Evidence of cyclic structure:
(1) In the presence of Nickel, benzene reacts with hydrogen to give cyclohexane, a six membered ring. This proves that benzene is a hexagonal
molecule with three double bonds.

(2) Benzene reacts with bromine in the presence of iron to give substituted C₆H₅Br. No isomers of C₆H₅Br was identified. On further reaction with bromine three isomeric disubstituted products C₆H₄Br₂ are formed. On this basis Kekule proposed that benzene consists of ring of carbon atoms with alternate single and double bonds.

4. Resonance description of benzene:
The phenomenon in which two or more structures can be written for a substance which has identical position ofatomsis called resonance. The actual structure of the molecule is said to be a resonance hybrid of various possible alternative structures. In benzene. Kekule’s structure (I) and (II) represented the resonance structures and structure (III) is the resonance hybrid of structure I and II.

5. Spectroscopic measurements:
X-ray and electron dîflìaction studies indicated that all carbon-carbon bonds are of equal length which is in between that of a single bond (1 .45Å ) and that of a double bond (1.34Å ).

6. Molecular orbital structure :
(1). Benzene is a flat hexagonal molecule with all carbons and hydrogen lying in the same plane with a bond angle of 120º. Each carbon atom has sp2 hybrid orbitais of carbon, overlap with each other and with s-orbitals of six hydrogen atoms forming six sigma (σ) C-H bonds and six sigma (σ) C – C bonds.

(2). All the σ-bonds in benzene lies in one plane with bond angle of 120º. Each C-atom in benzene possess an unhybridised p-orbital containing one electron. The lateral overlap of their p-orbitais produces 3π-bond, the six electrons of the p-orbitais cover all the six C-atoms and are said to be delocalised. Due to this delocalisation, strong π-bond is formed which makes the molecule stable.

7. Representation of benzene:
Hence, there are three ways is which benzene can be represented.

Question 3.
Explain the mechanism of the reaction between methane and chlorine.
Answer:
Methane reacts with chlorine in the presence of light which proceeds through the free radical chain mechanism. This mechanism is characterised by three steps: initiation, propagation and termination.

1. Chain initiation:
The chain is initiated by UV light, leading to homolytic fission of chlorine molecules into free radicals (chlorine atoms).

Here we choose Cl-Cl bond for fission because C- C and C-H bonds are stronger than Cl-Cl bond.

2. Chain propagation:
It proceeds as follows –
(a) Chlorine free radiais attack the methane molecule and breaks the C-H bond resulting in the generation of methyl free radicals.

(b) The methyl free radicals thus obtained attacks the second molecule of chlorine to give chloromethane (CH₃Cl) and a chlorine free radical as follows –

(c) This chlorine free radical then cycles back to step (a) and both steps (a) and (b) are repeated many times and thus a chain of reaction is set up.

3. Chain termination:
Aller sometime, the reaction stops due to the consumption of reactant and the chain is terminated by the combination of free radicals.

Question 4.
Write the mechanism for following reaction.

Answer:

The reaction proceeds through freee radical mechanism:

Step 1.
The weak O-O single bond linkage of peroxide undergoes homolytic cleavage to generate free radical.

Step 2.
The radicals abstracts a hydrogen atom from HBr thus generating bromine free radical.

Step 3.
The Bromine free radical adds lo the double bond in the way so as to form the more stable alkyl free radical,

Step 4.
Addition of HBr to secondary free radical.

Question 5.
Explain the acidic nature of alkynes.
Answer:
An alkyiic shows acidic nature only if it contains terminal hydrogen atom. This can be explained by considering the Sp hybrid orbitais of carbon atom in alkynes. The percentage of s-character of sp hybrid orbital (50%) is more than sp² hybrid orbital ofalkenes (33%) and sp³ hybrid orbital of alkanes (25%). Because of this, carbon atom becomes more electronegative, thus facilitating donation of H ions to bases. So hydrogen attached to triply bonded carbon atoms is acidic in nature.

Question 6.
Write the mechanism of chlorination of benzene.
Answer:
Step 1:
Generation of Cl^⊕ electrophile.
AlCl + Cl – Cl^⊕ + AlCl^Θ

Step 2:
Attack of the electrophile on the benzene ring to form arenium ion:

Step 3:
Rearomatisation of arenium ion:

Question 7.
Describe the mechanism of suiphonation of benzene.
Answer:
Step 1:
Generation of SO3 electrophile:
2H₂SO₄ → H₃O^⊕ + SO₃ + HSO₄^Θ

Step 2:
Attack of the electrophile on benzene ring to form arenium ion:

Step 3:
Rearomatisation of Areniurn ion:

Question 8.
Describe the mechanism of Freidel craft’s alkylation.
Answer:
Step 1:
Generation of ^⊕CH₃ electrophile:
AlCl₃ + CH₃Cl → ^⊕CH₃ + AlCl^Θ

Step 2 :
Attack of the electrophile on benzene ring to form areniurn ion:

Step 3:
Rearornatisation of arenium ion:

Question 9.
Write the mechanism of Freidel craft’s acylation.
Answer:
Step 1:
Generation of CH₃CO electrophile:

Step 2 :
Attack of the electrophile on benzene ring to form arenium ion.

Step 3 :
Rearomatisation of arenium ion:

Question 10.
An organic compound (A) of a molecular formula C₆H₆ which is a simple aromatic hydrocarbon. A undergoes hydrogenation to give a cyclic compound (B). A reacts with chlorine in the presence of UV-light to give C which is used as insecticide. Identify A, B and C. Explain the reactions with equation.
Answer:
1. Simple aromatic hydrocarbon, C₂H₆ is benzene.
2. Benzene (A) reacts with H₂ in the presence of Pt to give cyclohexane (B).

3. Benzene (A) reacts with Cl₂ in presence of UV-light to give benzene hexachioride (C).

Question 11.
What are ortho-para directors? Explain why -OH group is an ortho-para director and activator.
Answer;
The group which increases the electron density at ortho and para positions are called as ortho-para directors,
Example:
-OH. -NH₂ -NHR. -OCH₃, -CH₃, -C₂H₅ etc.

Let us consider the directive influence of phenolic group. Phenol is the resonance hybrid of the following structures:

In these resonance structures, the negative charge residue in the present at orilio and para positions of the ring structure. h is quite evident that the lone pair of electrons on the atom which is attached lo the ring is involved in resonance and it makes the ring more electron rich than benzene.

The electron density at oriho and para position increases as compared to the meta position. Therefore phenolic group activates the benzene ring for electrophilic attack at oriho and para positions. Hence 01-1 group is an orilio para director and activator.

Question 12.
An organic compound (A) of a molecular formula C₆H₆ is a simple aromatic hydrocarbon. A reacts with O₂ in the presence of VO₅ at 773 K to give B. A is further treated with sodium and liquid ammonia to give C which is a dienc compound. Identify A, B, and C and explain the reactions.
Answer:
1. A is benzene (C₆H₆), a simple aromatic hydrocarbon

2. Benzene (A) reacts with O₂ is the presence of V₂O₅ at 773K to give maleic anhydride (B).

3. Benzene (A) is treated with sodium and liquid ammonia to give 1.4 – cyclohexadiene (C)

Question 13.
What are inea drectors’? Explain with suitable example.
Answer:
The group which increases the electron density at mcta position are called as rneta directors.
For example:
-NO₂. -CN, -CHO, -COOH. -SO₃H etc.
Let us consider the directive influence of aldehydic (-CHO) group. Benzaldehyde is a resonence hybrid of the following structures.

In these resonance structures, the positive charge residue is present on the ring structure. It is quite evident that resonance deLocalises the positive charge on the atoms of the ring, making the ring less electron rich than henzene. Here overall electron density of benzene ring decreases due to -I effect of’ -CHO group, thereby deactivating the henzene for electrophilic atlack. However resonating structures shows that electron density is more at meto position as compared to ortho and para positions. Flence -CHO group is a ineta -director and a deactivator.

Question 14.
An organic compound (A) of molecular formula C₂H₄ which is a simple alkene reacts with Baeyer’s reagent to give B of molecular formula C₂H₆O₂ A again reacts with ozone followed by hydrolysis in the presence of zinc to form C of molecular formula CH₂O. Identify A, B and C. Explain with reactions.
Answer:
(i). A is CH₂ = CH₂ (Ethylene)

(ii). A (ethylene) reacts with Baeyer’s reagent (cold alkaline KMnO₄) to give ethylene glycol (ethane 1 ,2 diol).

Question 15.
An organic compound 1,1-dichioropropane reacts with aicholic KOH to give A of molecular formula C₃H₄. A reacts with mercuric sulphate and dil. H₂SO₄ at 333 K to give B. A on passing through red hot iron tube at 873 K will give C which is a cyclic compound. Identify A, B and C. Explain the reactions.
Answer:
1. 1,1-dichioropropane reacts with aicholic KOI-I to give propyne (A).

2. Propyne (A) reacts with mercuric sulphate and dil. H₂SO₄ at 333 K to give acetone (B).

3. Propyne (A) on passing through red hot iron tube at 873 K will give mesitylene (C).

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Samacheer Kalvi 11th Bio Zoology Trends in Economic Zoology Text Book Back Questions and Answers

Textbook Evaluation Solved
Choose The Correct Answer
Question 1.
Which one of the following is not related to vermiculture?
(i) Maintains soil fertility
(ii) Breakdown of inorganic matter
(iii) Gives porosity, aeration and moisture holding capacity
(iv) Degradation of non biodegradable solid waste
(a) (i) and (ii) is correct
(b) (iii) and (iv) is correct
(c) (ii) and (iv) is not correct
(d) (i) and (iii) is not correct
Answer:
(c) (ii) and (iv) is not correct

Question 2.
Which one of the following is not an endemic species of earthworm?
(a) Perionyx
(b) Lampito
(c) Eudrillus
(d) Octochaetona
Answer:
(c) Eudrillus

Question 3.
Match the following
(1) Bombyx mori – a) Champa – (1) Muga
(2) Antheraea assamensis – b) Mulberry – (II) Eri
(3) Antheraea mylitta – c) Arjun – (III)Tassar
(4) Attacus ricini – d) Castor – (IV) Mulberry Select the correct one.
(a) 1 – b – IV
(b) 2 – a – I
(c) 3 – c – III
(d) 4 – d – II
Answer:
(c) 3 – c – III

Question 4.
Silk is obtained from
(a) Laccifer lacca
(b) Nosema bombycis
(c) Attacus ricini
(d) Attacus mylitta
Answer:
(c) Attacus ricini

Question 5.
Assertion: Nuptial flight is a unique flight taken by the queen bee followed by several drones.
Reason: The queen bee produces a chemical substance called pheromone. The drones in that area are attracted to the pheromone and then mating takes place.
(a) Assertion and reason is correct but not related
(b) Assertion and reason is incorrect but related
(c) Assertion and reason is correct but related
(d) Assertion and reason is incorrect but not related
Answer:
(c) Assertion and reason is correct but related

Question 6.
Rearing of honey bee is called …………………..
(a) Sericulture
(b) Lac culture
(c) Vermiculture
(d) Apiculture
Answer:
(d) Apiculture

Question 7.
Which of the statement regarding Lac insect is TRUE?
(a) A microscopic, resinous crawling scale insect
(b) Inserts its proboscis into plant tissue suck juices and grows
(c) Secretes lac from the hind end of body
(d) The male lac insect is responsible for large scale production of lac
Answer:
(c) Secretes lac from the hind end of body

Question 8.
Aquaponics is a technique which is ……………….
(a) A combination of aquaculture and fish culture
(b) A combination of aquaculture and hydroponics
(c) A combination of vermiculture and hydroponics
(d) A combination of aquaculture and prawn culture
Answer:
(b) A combination of aquaculture and hydroponics

Question 9.
Prawn belongs to the class …………………
(a) Crustacea
(b) Annelida
(c) Coelenterata
(d) Echinodermata
Answer:
(a) Crustacea

Question 10.
Pearl oyster belongs to the Class …………………
(a) Gastropoda
(b) Cephalopoda
(c) Scaphapoda
(d) Pelecypoda
Answer:
(d) Pelecypoda

Question 11.
Inland fisheries are ………………..
(a) Deep sea fishing
(b) Capturing fishes from sea coast
(c) Raising and capturing fishes in fresh water
(d) Oil extraction from fish
Answer:
(c) Raising and capturing fishes in fresh water

Question 12.
Induced breeding technique is used in …………………
(a) Marine fishery
(b) Capture fishery
(c) Culture fishery
(d) Inland fishery
Answer:
(b) Capture fishery

Question 13.
Isinglass is used in …………………..
(a) Preparation
(b) Clearing of wines
(c) Distillation of wines
(d) Preservation of wines
Answer:
(b) Clearing of wines

Question 14.
Animal husbandry is the science of rearing, feeding and caring, breeding and disease control of animals. It ensures supply of proper nutrition to our growing population through activities like increased production and improvement of animal products like milk, eggs, meat, honey, etc.
(a) Poultry production depends upon the photoperiod. Discuss.
(b) Polyculture of fishes is of great importance.
Answer:

(a) Light is an important aspect in the poultry production. Light stimulates the secretion of FSH and LH. The wavelength between 400 and 700 nm is required. The decrease in the photoperiod will affect the egg production.

(b) A few selected fishes belonging to different species are stocked together in proper proportion in a pond. This mixed forming is termed as composite fish farming or polyculture. It is of great importance because

1. All available riches are fully utilized
2. Compatible species do not harm each other
3. There is no competition among different species

Question 15.
Assertion: The best quality of pearl is known as lingha pearl and obtained from marine oysters.
Reason: Nacre is secreted continuously by the epithelial layer of the mantle and deposited around the foreign particle.
(a) Assertion is true, Reason is false
(b) Assertion and Reason are false
(c) Assertion is false But Reason is true
(d) Assertion and Reason are true
Answer:
(c) Assertion is false But Reason is true

Question 16.
Choose the correctly matched pair.
(a) Egg layers – Brahma
(b) Broiler types – Leghorn
(c) Dual purpose – White Plymouth rock
(d) Ornamental breeds – Silkie
Answer:
(d) Ornamental breeds – Silkie

Question 17.
Write the advantages of vermicomposting?
Answer:

1. Vermicomposting provides excellent organic manure for sustainable agro-practices.
2. Marketing of vermicompost can provide a supplementary income.
3. Vermicompost is rich in essential plant nutrients.
4. It improves soil structure, texture, aeration, and water holding capacity and prevents soil erosion.
5. It is rich in nutrients and an eco-friendly amendment to soil for farming and terrace gardening,
6. It enhances seed germination and ensures good plant growth.

Question 18.
Name the three castes in a honey bee colony?
Answer:
The Queen, Drones and Workers.

Question 19.
Name the following?

1. The largest bee in the colony:
2. The kind of flight which the new virgin queen takes along with the drones out of the hive:

Answer:

1. The queen.
2. Nuptial flight.

Question 20.
What are the main duties of a worker bee?
Answer:
Each worker has to perform different types of work in her life time. During the first half of her life, she becomes a nurse bee attending to indoor duties such as secretion of royal jelly, prepares bee- bread to feed the larvae, feeds the queen, takes care of the queen and drones, secretes bees wax, builds combs, cleans and fans the bee hive. Then she becomes a soldier and guards the bee hive. In the second half her life lasting for three weeks, she searches and gathers the pollen, nectar,, propolis and water.

Question 21.
What happens to the drones after mating flight?
Answer:
They die after copulation.

Question 22.
Give the economic importance of Silkworm?
Answer:

1. Rearing of silkworm on a commercial scale is called sericulture.
2. It is an agro-based industry comprising of
   1. – Cultivation of food plants for the silkworms.
   2. – Rearing of silkworms.
   3. – Reeling and spinning of silk.
3. Silk fibres are utilized in preparing silk clothes.
4. Silk is used in industries and for military purposes.
5. Silk is used in the manufacture of fishing fibres, parachutes, cartridge bags, insulation coils for telephone, wireless receivers, tyres of racing cars, filter fibres, in medical dressings and as suture materials.

Question 23.
What are the Nutritive values of fishes?
Answer:
Economic importance of fish:-
Fishes form a rich source of protein food and provide a good staple food to tide over the nutritional needs of man. Fish species such as sardines, mackerel, tuna, herrings have high amino acids concentration particularly histidine which is responsible for the meaty flavor of the flesh. It is rich in fat such as omega 3 fatty acids. Minerals such as calcium, magnesium, phosphorus, potassium, iron, manganese, iodine and copper.

Some of the fish by-products are: Fish oil is the most important fish by-product. It is derived from fish liver and from the fish body.

Fish liver oil is derived from the liver which is rich in vitamin A and D, whereas fish body oil has high content of iodine, not suitable for human consumption, but is used in the manufacture of laundry soaps, paints and cosmetics. Fish meal is prepared from fish waste after extracting oil from the fish.

The dried wastes are used to prepare food for pig, poultry and cattle. The wastes obtained during the preparation of fish meal are widely used as manure.

Isinglass is a high-grade collagen produced from dried air bladder or swim bladder of certain fishes viz. catfish and carps. The processed bladder which is dissolved in hot water forms a gelatin having adhesive property. It is primarily used for clarification of wine, beer and vinegar.

Question 24.
Give the economic importance of prawn fishery?
Answer:
The flesh of prawn is palatable and rich in glycogen, protein with low fat content.

Question 25.
Give the economic importance of lac insect?
Answer:
Economic importance of Lac:-

1. Lac is largely used as a sealing wax and adhesive for optical instruments. It is used in electric industry, as it is a good insulator.
2. It is used in preparations of shoe and leather polishes and as a protective coating of wood.
3. It is used in laminating paper board, photographs, engraved materials and plastic moulded articles.
4. Used as a filling material for gold ornaments.

Question 26.
List any three common uses of shellac?
Answer:

1. Shellac with denatured alcohol is used to remove dust on the walls.
2. Coating of metals with shellac prevents rusting.
3. Shellac coating on citrus fruits increases their shelf life.

Question 27.
Name any two trees on which lac insect grows?
Answer:
Acacia catechu, Acacia nilotica.

Question 28.
What is seed lac?
Answer:
Lac cut from the host plant is called ‘stick lac’. The lac present on the twig is scraped and collected. After grinding, the unnecessary materials like dusts and fine particles are removed. The resultant lac is called ‘seed lac’.

Question 29.
Define cross breeding?
Answer:
Breeding between a superior male of one breed with a superior female of another breed is known as cross breeding.

Question 30.
What are the advantages of artificial insemination?
Answer:
Advantages of artificial insemination:

1. It increases the rate of conception
2. It avoids genital diseases
3. Semen can be collected from injured bulls which have desirable traits
4. Superior animals located apart can be bred successfully

Question 31.
Discuss the various techniques adopted in cattle breeding?
Answer:
There are two methods of animal breeding, namely inbreeding and outbreeding.
1. Inbreeding:
Breeding between animals of the same breed for 4-6 generations is called inbreeding.

2. Outbreeding:
The breeding between unrelated animals is called outbreeding. It is done in three ways;

• Out crossing: It is the breeding between unrelated animals of the same breed but having no common ancestry. The offspring of such a cross is called outcross.
• Cross breeding: Breeding between a superior male of one breed with a superior female of another breed. The cross bred progeny has superior traits (hybrid vigour or heterosis).
• Interspecific hybridization: In this method of breeding mating is between male and female of two different species.

Question 32.
Mention the advantages of MOET?
Answer:
Multiple Ovulation Embryo Transfer Technology (MOET) is a method of propagation of animals with desirable traits. This technology is used to produce high milk yielding females and high quality meat yielding bulls in a short time.

Question 33.
Write the peculiar characters of duck?
Answer:
Peculiarity of ducks:
The ducks body is fully covered with oily feathers. They have a layer of fat under their skin which prevents it from getting wet. They lay eggs at night or in the morning. The ducks feed on rice bran, kitchen wastes, waste fish and snails.

In – Questions Solved

Question 1.
My vennicompost manufacturing unit is plagued by a number of red ants. Are there any bio-friendly measures to tackle the menace as I do not want to use any chemicals?
Answer:
There are few bio-friendly measures to tackle the menace. For eg. Sprinkling of cinnamon powder or cloves can repel ants.

Question 2.
India has the distinction of producing all the four types of silk i.e.
(a) Mulberry silk (9-1.7%)
(b) Tasar silk (1.4%)
(c) Eri silk (6.4%) and
(d) Muga silk (0.5%) which are produced by different species of silkworms. Name the species that produces large amount and least amount of silk in India?
Answer:
Bombyx mori produces large amount of silk in India and Antheraea assamensis produces least amount of silk in India.

Question 3.
(a) Growing fish or other aquatic animals and plants together in an integrated system. The fish wastes provides nutrients for the plants and the plants filter the water. Additionally bacteria break down by-products such as ammonia?
(b) Growing plants in a nutrient solution instead of soil. Fish kept in the water provide the required nutrients. Write the appropriate scientific terms for above (a) and (b) and differentiate between them?
Answer:
(a) Aquaponics
(b) Hydroponics

Question 4.
Why are fish so efficient at converting feed to flesh?
Answer:
Fish is more efficient in converting a greater proportion of feed they receive into flesh because as fish live in water they expend less energy to maintain internal body temperature and also by excreting a more simple form of urine (ammonia).

Samacheer Kalvi 11th Bio Zoology Trends in Economic Zoology Additional Questions & Answers

I. Choose The Correct Answer

Question 1.
During the process of vermiculture which of the following does not happen?
(a) Decomposition of organic food waste
(b) Supplying nutrients to the soil
(c) Use of earthworms in the process
(d) Synthesis of organic substances
Answer:
(d) Synthesis of organic substances

Question 2.
The breakdown of organic matter by the activity of the earthworms and its elimination from its body is called …………….
(a) Vermitech
(b) Vermicast
(c) Vermicompost
(d) Vermiculture
Answer:
(b) Vermicast

Question 3.
The technology of composting and bioremediation of soils and other activities by application of earthworm is called? …………………
(a) Vermitech
(b) Vermicast
(c) Vermicompost
(d) Vermiculture
Answer:
(a) Vermitech

Question 4.
Which is not related to humus formers?
(a) They are darker in colour
(b) They feed on organic matter
(c) They make the soil porous
(d) They are surface dwellers
Answer:
(c) They make the soil porous

Question 5.
Which of the following is the exotic species used for vermicomposting?
(a) Eudrilus eugeniae
(b) Lampito mauritii
(c) Periyonyx excavatus
(d) Octochaetona serrata
Answer:
(a) Eudrilus eugeniae

Question 6.
Antheraea mylitta feeds on ……………
(a) Mulberry
(b) Arjun
(c) Castor
(d) Champa
Answer:
(b) Arjun

Question 7.
Attacus ricini produces ……………. silk?
(a) Muga
(b) Tassar
(c) Mulberry
(d) Eri
Answer:
(d) Eri

Question 8.
The process of killing the cocoons is called ……………..
(a) Reeling
(b) Stifling
(c) Rearing
(d) Culturing
Answer:
(b) Stifling

Question 9.
Febrine is a dangerous disease to silkworms caused by ………………
(a) Streptococceus
(b) Nosema bombycis
(c) BmNPV
(d) Beauveria bassiana
Answer:
(b) Nosema bombycis

Question 10.
Muscardine is a- disease of silkworms caused by a …………………..
(a) Bacterium
(b) Virus
(c) Protozoan
(d) Fungus
Answer:
(d) Fungus

Question 11.
Among the honey bees, workers are ………………..
(a) Fertile females
(b) Fertile males
(c) Sterile females
(d) Sterile males
Answer:
(c) Sterile females

Question 12.
Honey is used as ………………..
(1) An antiseptic
(2) A laxative
(3) A sedative
(4) A substitute for sugar
(a) 1, 2, 3 only
(b) 2, 3, 4 only
(c) 2,4 only
(d) 1, 2, 3, & 4
Answer:
(d) 1, 2, 3, & 4

Question 13.
Lac is secreted by lac insect for ………………
(a) Growth
(b) Development
(c) Protection
(d) Moulting
Answer:
(c) Protection

Question 14.
Growing plants in non-soil media and nutrient-laden water is called ……………….
(a) Aquaponics
(b) Hydroponics
(c) Aquaculture
(d) Apiculture
Answer:
(b) Hydroponics

Question 15.
Raft based method of aquaponic gardening is known as ………………..
(a) Deep water culture
(b) Aqua vertica
(c) Media based method
(d) Nutrient film technique
Answer:
(a) Deep water culture

Question 16.
Culturing of animals in the water having salinity range 0.5-30 ppt are called as ………………
(a) Freshwater aquaculture
(b) Marine water aquaculture
(c) Brackish water aquaculture
(d) Metahaline culture
Answer:
(c) Brackish water aquaculture

Question 17.
Culturing of animals in the water salinity ranges from 30-35% is called ……………
(a) Brackish water aquaculture
(b) Mariculture
(c) Metahalive culture
(d) Fresh water aquaculture
Answer:
(b) Mariculture

Question 18.
Labeo and catla belong to ………………. fishes?
(a) Indigenous fresh water
(b) Salt water
(c) Exotic
(d) Brackish water
Answer:
(a) Indigenous fresh water

Question 19.
In composite fish farming …………………. are stocked together in proper proportion in a pond?
(a) Different species of fishes
(b) Fishes of the same species
(c) All animals
(d) All plants and animals
Answer:
(a) Different species of fishes

Question 20.
Fish liver oil is rich in vitamins ……………
(a) A & B
(b) A & C
(c) A & D
(d) A & E
Answer:
(c) A & D

Question 21.
The best quality of pearl is obtained from …………… oysters?
(a) Land
(b) Brackish water
(c) Fresh water
(d) Marine
Answer:
(d) Marine

Question 22.
Breeding between animals of the same breed for 4-6 generation is called ……………
(a) Outbreeding
(b) Inbreeding
(c) Cross breeding
(d) Outcrossing
Answer:
(A) Inbreeding

Question 23.
The breeding between unrelated animals is called ……………
(a) Inbreeding
(b) Cross breeding
(c) Outbreeding
(d) Outcrossing
Answer:
(c) Outbreeding

Question 24.
Breeding between a superior male of one breed with a superior female of another breed is called ……………
(a) Inbreeding
(b) Outbreeding
(c) Outcrossing
(d) Cross breeding
Answer:
(d) Cross breeding

Question 25.
Jersy is a breed?
(a) Milch
(b) Drought purpose
(c) Dual purpose
(d) Common
Answer:
(a) Milch

Question 26.
Leghorns are preferred in commercial farms because ……………
(a) They give good quality flesh
(b) They mature late
(c) They mature early and begin to lay eggs at the age of 5 months
(d) They look beautiful
Answer:
(c) They mature early and begin to lay eggs at the age of 5 months

Question 27.
…………… is a dual purpose chicken breed?
(a) Aseel
(b) Silkie
(c) Brahma
(d) White plymouth rock
Answer:
(c) Brahma

Question 28.
The incubation period of chick embryo development is …………… days?
(a) 10-12
(b) 21-22
(c) 25-30
(d) 15-17
Answer:
(b) 21-22

Question 29.
Ranikhet, Coccidiosis and Fowl pox are ……………
(a) Chicken breeds
(b) Types of poultry farming
(c) Poultry diseases
(d) Types of breeding methods
Answer:
(c) Poultry diseases

Question 30.
Which of the following is the native breed of duck?
(a) Pekin
(b) Campbell
(c) Muscori
(d) Syhlet meta
Answer:
(d) Syhlet meta

II. Fill in the Blanks

Question 1.
…………… are called as ‘farmer’s friends’.
Answer:
(Earthworms)

Question 2.
The breakdown of organic matter by the activity of the earthworms and its elimination from its body is called ……………
Answer:
(Vermicast)

Question 3.
Humus feeders are …………… worms.
Answer:
(Burrowing)

Question 4.
…………… are the earthworms used for vermicomposting.
Answer:
(Humus feeders)

Question 5.
The exotic species of earthworms are ……………
Answer:
(Eisenia fetida/Eudrilus eugeniae)

Question 6.
…………… is a liquid collected after the passage of water through a column of vermibed.
Answer:
(Vermiwash)

Question 7.
Vermiwash is obtained from formed by earthworms.
Answer:
(Burrows/drilospheres)

Question 8.
Production of silk from the silkworm by rearing practices on a commercial scale is called ……………
Answer:
(Sericulture)

Question 9.
The eggs of silkworms after ten days of incubation hatch into larva called as ……………
Answer:
(Caterpillar)

Question 10.
The cultivation of mulberry is called as ……………
Answer:
(Moriculture)

Question 11.
The process of killing the cocoons is called ……………
Answer:
(Stifling)

Question 12.
The process of removing the threads of silk from the killed cocoon is called ……………
Answer:
(Reeling)

Question 13.
Nosema bombycis causes …………… to silkworms,
Answer:
(Pobrine)

Question 14.
…………… is the viral disease of Bombyx mori caused by BmNPV.
Answer:
(Grasserie)

Question 15.
White muscardine is caused by a fungus
Answer:
(Beauveria bassiana)

Question 16.
Apiculture is the care and management of on a commercial scale.
Answer:
(honeybees)

Question 17.
…………… is the Indian honey bee,
Answer:
(Apis indica)

Question 18.
…………… is the rock bee.
Answer:
(Apis dorsata)

Question 19.
…………… is the little bee.
Answer:
(Apisflorea)

Question 20.
Apis mellifera is the …………… bee.
Answer:
(European)

Question 21.
……………. is the functional female bee present in each bee hive.
Answer:
(Queen)

Question 22.
The Queen bee produces …………… to attract drones.
Answer:
(Pheromone)

Question 23.
Among the honey bees, are sterile females.
Answer:
(Workers)

Question 24.
………………. is the functional male member of the honey bee colony.
Answer:
(Drone)

Question 25.
A unique flight by the queen bee followed by several drones is called ……………
Answer:
(Nuptial flight)

Question 26.
The process of leaving the colony by the queen with a large group of worker bees to form a new colony is called ……………
Answer:
(Swarming)

Question 27.
Honey is used as an antiseptic, laxative and as a ……………
Answer:
(Sedative)

Question 28.
The resinous chemical substance present in the bee wax is called ……………
Answer:
(Propolis)

Question 29.
Lac is produced by the lac insect
Answer:
(Laccifer lacca/Tachardia lacca)

Question 30.
Karanagalli is the host plant for ……………
Answer:
(Lac insect)

Question 31.
The mass emergence of larvae from the eggs of lac in search of a host plant is called ……………
Answer:
(Swarming)

Question 32.
A condition in which a secondary parasite develops within a previously existing parasite is called ……………
Answer:
(Hyper-parasitism)

Question 33.
The collection of lac from the host plant is known as ……………
Answer:
(Harvesting)

Question 34.
Lac cut from the host plant is called ……………
Answer:
(Stick lac)

Question 35.
The seed lac is sundried and then melted to produce ……………
Answer:
(Shellac)

Question 36.
Growing fish is known as ……………
Answer:
(Aquaculture)

Question 37.
Chanos chanos are cultured in ……………
Answer:
(Brackish water)

Question 38.
Culturing of animals in the salinity ranges from 36-40% is called …………… culture.
Answer:
(Metahaline)

Question 39.
…………… is commonly known as the brine shrimp.
Answer:
(Artemia)

Question 40.
Catla, Labeo are fresh water fishes.
Answer:
(Native/indigenous)

Question 41.
Fish oil is derived from the …………… of fish.
Answer:
(Liver)

Question 42.
……………… is prepared from fish waste after extracting oil from the fish.
Answer:
(Fish meal)

Question 43.
………………. is a high grade collagen produced from dried air bladder of catfish.
Answer:
(Isinglass)

Question 44.
Prawn is rich in …………… protein with low fat content.
Answer:
(Glycogen)

Question 45.
Most of the marine prawns caught along the Indian coast belongs to the family ……………
Answer:
(Penaeidae)

Question 46.
Metapenaeus dobsoni is a species of ……………
Answer:
(Prawn)

Question 47.
Fresh water bivalve …………… is used in artificial pearl culture.
Answer:
(Lamellidens)

Question 48.
The piece of tissue which is inserted inside the mantle of the oyster is called as …………… tissue.
Answer:
(Graft)

Question 49.
90% of pearl is ……………
Answer:
(Calcium carbonate)

Question 50.
The best quality of pearl is obtained from …………… oysters.
Answer:
(Marine)

Question 51.
The practice of breeding and raising livestock is called as ……………
Answer:
(Animal husbandry)

Question 52.
……………… increases homozygosity and exposes harmful recessive genes.
Answer:
(Inbreeding)

Question 53.
…………… helps to produce new and favourable traits, new breeds and hybrids-with superior qualities
Answer:
(Outbreeding)

Question 54.
……………….. is a technique in which the semen collected from the male is injected to the reproductive tract of the selected female.
Answer:
(Artificial insemination)

Question 55.
…………… is the production and marketing of milk and its products.
Answer:
(Dairying)

Question 56.
Sindhi, Gir, Jersy are …………… breeds.
Answer:
(Dairy/Milch)

Question 57.
…………… is the rearing and propagation of avian species.
Answer:
(Poultry)

Question 58.
…………… is the type of chicken breeds well known for fast growth and soft quality meat.
Answer:
(Broiler)

Question 59.
Caring and management of young chicks for 4-6 weeks immediately after hatching is called ……………
Answer:
(Brooding)

Question 60.
Ranikhet is a …………… disease.
Answer:
(Poultry)

Question 61.
Domesticated ducks have been derived from the wild duck named ……………
Answer:
(Anas Aoscav/Mallard)

Question 62.
Droppings of poultry can be used as in …………… fields.
Answer:
(Manure)

Question 63.
The droppings of poultry are rich in nitrogen, potash and ……………
Answer:
(Phosphates)

Question 64.
The eggs and poultry meat are the richest sources of …………… and vitamins.
Answer:
(Proteins)

III. Answer The Following Questions

Question 1.
What is Economic Zoology?
Answer:
Economic zoology is a branch of Science that deals with economically useful animals. It involves the study of application of animals for human welfare.

Question 2.
How are animals classified on the basis of economic importance?
Answer:

1. Animals for food and food products
2. Economically beneficial animals
3. Animals of aesthetic importance
4. Animals for scientific research

Question 3.
What is Vermiculture?
Answer:
Vermiculture is the process of using earthworms to decompose organic food waste, into a nutrient-rich material capable of supplying necessary nutrients which helps to sustain plant growth.

Question 4.
What is Vermitech?
Answer:
Applications of earthworm in technology of composting and bioremediation of soils and other activities is called Vermitech.

Question 5.
Why are earthworms called as ‘friends of farmers’?
Answer:
Earthworms play a vital role in maintaining soil fertility. Hence, they are called as ‘friends of farmers’.

Question 6.
What is Vermicast?
Answer:
The breakdown of organic matter by the activity of the earthworms and its elimination from its body is called vermicast.

Question 7.
What are the different groups of earthworms?
Answer:
There are two major groups of earthworms. The humus formers dwell on the surface and feed on organic matter. They are generally darker in colour. They are used for vermicomposting. The humus feeders are burrowing worms that are useful in making the soil porous and mixing and distributing humus throughout the soil.

Question 8.
What are endemic species and exotic species of earthworms?
Answer:
The native species of earthworms cultured in India for vermicomposting such as Periyonyx excavatus, Lampito mauritii, Octochaetona serrata are endemic species. Some earthworm species introduced from other countries such as Eisenia fetida, Eudrilus eugeniae are exotic species.

Question 9.
What is Vermicompost?
Answer:
Vermicompost is. the compost produced by the action of earthworms in association with all other organisms in the compost unit.

Question 10.
Write a note on Vermiwash?
Answer:
Vermiwash is a liquid collected after the passage of water through a column of vermibed. It is useful as a foliar spray to enhance plant growth and yield. It is obtained from the burrows or drilospheres formed by earthworms. Nutrients, plant growth promoter substances and some useful microorganisms are present in vermiwash.

Question 11.
What are the pests of earthworms?
Answer:
Ants, springtails, centipedes, slugs, mites, certain beetle larvae, birds, rats, snakes, mice, toads and other insects or animals which feed on worms.

Question 12.
What, are the internal parasites of earthworms?
Answer:
Protozoans, some nematodes and the larvae of certain flies.

Question 13.
What are the advantages of vermicompost?
Answer:

1. Vermicompost is rich in essential plant nutrients.
2. It improves soil structure texture, aeration, and water holding capacity and prevents soil erosion.
3. Vermicompost is rich in nutrients and an eco-friendly amendment to soil for farming and terrace gardening.
4. It enhances seed germination and ensures good plant growth.

Question 14.
What is sericulture?
Answer:
Sericulture is an agro-based industry which denotes commercial production of silk through silkworm rearing.

Question 15.
What are the components of sericulture?
Answer:

1. Cultivation of food plants for the silkworms,
2. Rearing of silkworms, and
3. Reeling and spinning of silk.

The first two are agricultural and the last one is an industrial component. Only felt species of silkworms are used in the sericulture industry.

Question 16.
Tabulate the different types of silkworm?
Answer:

Question 17.
What are the various races of Bombyx mori?
Answer:
On the basis of the moults they undergo in the larval stage, B. mori is divided into three races. They are:

1. Tri moulters – 3 moults
2. Tetra moulters – 4 moults
3. Penta moulters – 5 moults
   • On the basis of voltinism (the number of broods raised per year), three kinds of races are recognised. They are:
   • Univoltines – one brood only
   • Bivoltines – two broods only
   • Multivoltines – more than two broods

Question 18.
What is Moriculture?
Answer:
The cultivation of mulberry is called as Moriculture.

Question 19.
What are the improved mulberry varieties?
Answer:
Victory 1, S3 6, G2 and G4

Question 20.
What is the favourable season for cultivating mulberry plants?
Answer:
June, July, November and December

Question 21.
What is stifling?
Answer:
The process of killing the cocoons is called stifling,

Question 22.
What is reeling?
Answer:
The process of removing the threads from the killed cocoon is called reeling.

Question 23.
What is cooking?
Answer:
The process of soaking cocoons in hot water (95° – 97°) for 10 – 15 minutes to soften the gum that binds the silk threads together is called as cooking.

Question 24.
What are the uses of silk?
Answer:
Uses of Silk:-
1. Silk fibers are utilized in preparing silk clothes. Silk fibers are now combined with other natural or synthetic fibers to manufacture clothes like Teri-Silk, Cot-Silk etc. Silk is dyed and printed to prepare ornamented fabrics. They are generally made from Eri-silk or spun silk.

2. Silk is used in industries and for military purposes.

3. It is used in the manufacture of fishing fibers, parachutes, cartridge bags, insulation coils for telephone, wireless receivers, tyres of racing cars, filter fibres, in medical dressings and as suture materials.

Question 25.
Write a note on the diseases and pests of silkworms? Diseases and Pests of Silkworm?
Answer:
The profitable silk industry is threatened by various diseases caused by the virus, fungal, bacterial and protozoan infections but also by insect predators, birds and other higher animals. Ants, crows, kites, rats, feed upon silkworms thereby causing a great loss to silk industry.

Pebrine, is a dangerous disease to silkworms and the causative organism is Nosema bombycis, a protozoan. This silkworm disease is transmitted through the egg of the mother silkworm and also through ingestion of contaminated food.

Flacherie generally occurs in the mature larvae and is caused mainly by bacteria like Streptococcus and Staphylococcus. Grasserie is a most dominant and serious viral disease.

It is caused by Bombyx mori nuclear polyhedrosis virus (BmNPV) a Baculovinis, which belongs to sub group ‘A’ of the Baculoviridae. Among the fungal diseases, white muscardine is common. This disease is caused by fungus Beauveria bassiana.

Question 26.
What is Apiculture?
Answer:
Care and management of honey bees on a commercial scale for the production of honey is called Apiculture or Bee keeping.

Question 27.
What are the types of bees?
Answer:

1. Apis dorsata – Rock bee
2. Apisflorea – Little bee
3. Apisindica – Indian bee
4. Apis mellifera – European bee
5. Apis adamsoni – African bee

Question 28.
Comment on the social organization of honey bees?
Answer:
In honey bees, a highly organized division of labour is found. A well developed honey bee colony consists of the Queen, Drones and Workers. All the three types depend on each other for their existence. There is normally one queen, 10,000 to 30,000 workers and few hundred drones (male bees) in a colony.

Question 29.
Write a note on Queen, Worker and Drones?
Answer:
Queen:

1. It is a functional female present in each hive.
2. It feeds on royal jelly.
3. Its function is to lay eggs throughout its life span.
4. It lays about 15 lakh eggs.

Workers:

1. Workers are sterile females and the smallest of all the bees.
2. Each worker bee secretes royal jelly, prepares bee-bread to feed the larvae, feeds the queen, takes care of the queen and drones, secretes bee wax, builds combs, cleans and fans the bee hive.
3. It guards the bee hive, gathers pollen, nectar, propolis and water.

Drones:

1. Drones are the fuctional male members of the colony.
2. The sole duty of the drone is to fertilize the virgin queen and hence called ‘king of the colony’.

Question 30.
What is nuptial flight?
Answer:
During the breeding season in winter, a unique flight taken by the queen bee followed by , several drones is called nuptial flight.

Question 31.
Explain the structure of a bee hive?
Answer:
Structure of a Bee Hive. The house of honey bee is termed as bee hive or comb. The hive consists of hexagonal cells made up of wax secreted by the abdomen of worker bees arranged in opposite rows on a common base. These hives are found hanging vertically from the rocks, building or branches of trees . The young stages of honey bees accommodate the lower and central cells of the hive called the brood cells.

In Apis dorsata, the brood cells are similar in size and shape but in other species, brood cells are of three types viz., queen cell for queens, worker cell for workers and drone cells for drones. The cells are intended for storage of honey and pollen in the upper portion of the comb whereas the lower portions are for brood rearing.

Question 32.
Explain the parts of the Langstroth bee hive?
Answer:
The Langstroth bee hive is made up of wood and consists of six parts.
(1) Stand is the basal part of the hive on which the hive is constructed. The stands are adjusted to make a slope for rain water to drain

(2) Bottom board is situated above the stand and forms the proper base for the hive. It has two gates, one gate functions as an entrance while the other acts as an exit.

(3) Brood chamber is the most important part of the hive. It is provided with 5 to 10 frames arranged one above the other through which the workers can easily pass. The frame is composed of wax sheet which is held in vertical position up by a couple of wires. Every sheet of wax is known as Comb Foundation. The comb foundation helps in obtaining a regular strong worker brood cell comb which can be used repeatedly.

(4) Super is also a chamber without cover and base. It is provided with many frames containing comb foundation to provide additional space for expansion of the hive. 5) Inner cover is a wooden piece used for covering the super with many holes for proper ventilation. 6) Top cover is meant for protecting the colonies from rains. It is covered with a sheet which is plain and sloping.

Question 33.
What is comb foundation?
Answer:
Comb foundation is a sheet of bee wax, on both sides of which the exact shape of different cells of the comb is made in advance.

Question 34.
What is the use of Bee gloves?
Answer:
Bee gloves are used by bee keepers for protecting their hands while inspecting the hives.

Question 35.
What is Bee veil?
Answer:
Bee veil is a device made of fine nettings to protect the bee-keeper from bee sting.

Question 36.
What is the use of Smoker?
Answer:
Smoker is used to scare the bees during hive maintenance and honey collection by releasing smoke.

Question 37.
What is hive tool?
Answer:
Hive Tool is a flat, narrow and long piece of iron which helps in scraping excess propolis or wax from hive parts. . .

Question 38.
What is the use of:
(a) Uncapping knife
(b) Bee brush
(c) Queen introducing cage
(d) Feeders
(e) Honey Extractor
(f) Hive Entrance Guard
Answer:
(a) Uncapping knife:
Uncapping knife is a long knife which helps in removing the cap from the combs as a first step in honey extraction.

(b) Bee Brush:
Bee brush is a large brush often employed to brush off bees from honey combs particularly at the time of extraction.

(c) Queen introducing cage:
Queen introducing cage is a pipe made of wire nets used for keeping the queen for about 24 hours for acquaintance with the hive and worker bees.

(d) Feeder:
Feeder is a basin with sugar syrup covered by grass to feed the bees during drought season. The grass prevents the bees from sinking into the syrup.

(e) Honey Extractor:
Honey Extractor is a stainless-steel device which spins the combs rapidly to extract honey.

(f) Hive Entrance Guard:
Hive Entrance Guard is a device similar to queen excluder in front of the hive entrance which prevents the escape of queen during warming season.

Question 39.
What are the products of bee keeping?
Answer:
Products of bee keeping and their economic importance. The chief products of bee keeping industry are honey and bee wax. Honey is the healthier substitute for sugar.

The major constituents of honey are: levulose, dextrose, maltose, other sugars, enzymes, pigments, ash and water. It is an aromatic sweet material derived from nectar of plants. It is a natural food, the smell and taste depends upon the pollen taken by the honey bee. It is used as an antiseptic, laxative and as a sedative.

It is generally used in Ayurvedic and Unani systems of medicine. It is also used in the preparation of cakes, breads and biscuits. Bee wax is secreted by the abdomen of the worker bees at the age of two weeks. The wax is masticated and mixed with the secretions of the cephalic glands to convert it into a plastic resinous substance.

The resinous chemical substance present in the wax is called propolis which is derived from pollen grains. The pure wax is white in colour and the yellow colour is due to the presence of carotenoid pigments. It is used for making candles, water proofing materials, polishes for floors, furniture, appliances, leather and taps. It is also used for the production of comb foundation sheets in bee keeping and used in pharmaceutical industries.

Question 40.
What is Lac culture?
Answer:
The culture of lac insect using techniques for the procurement of lac on large scale is known as Lac culture.

Question 41.
Name the insect that produces Lac?
Answer:
Tachardia lacca.

Question 42.
What is ‘swarming’?
Answer:
The mass emergence of larvae from the egg in search of a host plant is called ‘swarming’.

Question 43.
What is hyper-parasitism?
Answer:
Hyper-parasitism – A condition in which a secondary parasite develops within a previously existing parasite.

Question 44.
What is harvesting? Write on the types of lac?
Answer:
The collection of lac from the host plant is known as harvesting. Harvesting may be done before swarming (immature) or after swarming (mature). Immature harvesting produces ‘Ari lac’ whereas mature harvesting produces the mature lac. Lac cut from the host plant is called ‘Stick lac’.

The lac present on the twig is scraped and collected. After grinding, the unnecessary materials like dusts and fine particles are removed. The resultant lac is called ‘seed lac’. The seed lac is sun dried and then melted to produce ‘shellac’.

Question 45.
What is Aquaponics?
Answer:
Aquaponics is a technique which is a combination of aquaculture (growing fish)’ and hydroponics (growing plants in non-soil media and nutrient-laden water).

Question 46.
What are the methods of aquaponic gardening?
Answer:
(i) Deep water culture is otherwise known as raft based method. In this method a raft floats in water. Plants are kept in the holes of raft and the roots float in water. This method is applicable for larger commercial scale system. By this, method fast growing plants are cultivated.

(ii) Media based method involves growing plants in inert planting media like clay pellets or shales. This method is applicable for home and hobby scale system. Larger number of fruiting plants, leafy green plants, herbs and other varieties of plants can be cultivated.

(iii) Nutrient Film technique involves the passage of nutrient rich water through a narrow trough or PVC pipe. Plants are kept in the holes of the pipe to allow the roots to be in free contact with in the water stream.

(iv) Aqua vertica is otherwise known as vertical aquaponics. Plants are stacked on the top of each other in tower systems. Water flows in through the top of the tower. This method is suitable for growing leafy greens, strawberries and other crops that do not need supporting solid substratum to grow.

Question 47.
What are the advantages of Aquaponic gardening?
Answer:
Advantages of Aquaponic gardening.
Water conservation:
No need of water discharge and recharge as the water is maintained by recycling process.

Soil:
Bottom soil may be loaded with freshwater. Microbes in water can convert the waste materials into usable forms like ammonia into nitrates which are used by the plants. Thus the soil fertility is maintained.

Pesticides:
In this system use of pesticides is avoided and hence it is eco-friendly.

Weeds:
Since the plants are cultured in confined conditions, growth of weeds is completely absent. The utilization of nutrient by plants is high in this method.

Artificial food for fishes:
In this system plant waste and decays are utilized by fishes as food. So, the need for the use of supplementary feed can be minimized.

Fertilizer usage:
Artificial or chemical fertilizers is not required for this system since the plants in the aquaponics utilize the nutrients from the fish wastes dissolved in water.

Question 48.
What are the fauna and flora cultured and cultivated in aquaponics?
Answer:
Cultivable fishes like tilapia, trout, koi, gold fish, bass etc., are cultured in aquaponics. Common cultivable plants like tomato, pepper, lettuce, cucumber, and rose are co-cultivated in this method.

Question 49.
What is aquaculture?
Answer:
Aquaculture is a branch of science that deals with the farming of aquatic organisms such as fish, molluscs, crustaceans and aquatic plants.

Question 50.
What are the three types of aquaculture on the basis of the source?
Answer:
On the basis of source, aquaculture can be classified into three categories. They are

1. Freshwater aquaculture
2. Brackish water aquaculture
3. Marine water aquaculture.

Question 51.
What is pisciculture?
Answer:
Culturing of fishes is called fish culture or pisciculture.

Question 52.
What should be the pH and salinity of freshwater used for aquaculture?
Answer:
pH of the freshwater should be around neutral and salinity below 5ppt.

Question 53.
Write a short note on Brackish water fishes?
Answer:
Brackish water fishes spend most of its life in river mouths (estuaries) back waters, mangrove swamps and coastal lagoons. Estuarine fish are more common in Bengal and Kerala. Culturing of animals in the water having salinity range 0.5 – 30 ppt are called as brackish water culture. Fishes cultured in brackish water are Milk fish (Chanos Chanos), Sea bass (‘Koduva’), Grey mullet (‘Madavai’), Pearl spots (‘Kari’meen) etc.

Question 54.
What are the varieties of marine fisheries?
Answer:
Mackerels, sardines, sharks, catfish.

Question 55.
What is Mariculture?
Answer:
Culturing of animals in the water salinity ranges from 30 – 35% is called Mariculture. Some fishes like Chanos sp, Mugil cephalus are cultured here.

Question 56.
What is Metahaline culture?
Answer:
Culturing of animals in the water salinity ranges from 36 – 40% is called Metahaline culture. Eg, Brine shrimp (Artemia salina).

Question 57.
What is Artemia?
Answer:
Artemia is commonly known as the brine shrimp. It is a crustacean and lives in high saline waters because of its high osmoregulatory capacity.

Question 58.
What are the characteristics of cultivable fishes?
Answer:
Characteristics of cultivable fishes.
The special characteristic features of cultivable fishes are:

1. Fishes should have high growth rate in short period of culture.
2. They should accept supplementary diet. ‘
3. They should be hardy enough to resist some common diseases and infection of parasites.
4. Fishes proposed for poly culture should be able to live together without interfering or attacking other fishes.
5. They should have high conversion efficiency so that they can effectively utilize the food.

Question 59.
What are the types of cultivable fishes?
Answer:
Types of cultivable fish:
Cultivable fish are of 3 types:-

1. Indigenous or native fresh water fishes (Major carps, Catla, Labeo, Clarias).
2. Salt water fishes acclimatized for fresh water (Chanos, Mullet).
3. Exotic fishes are imported from other counties (Common carps).

Question 60.
What are the reasons for culturing carps in India?
Answer:
Major carps have proved to be best suited for culture in India, because the carps

1. Feed on zooplanktons and phytoplanktons, decaying weeds, debris and other aquatic plants.
2. They can survive in turbid water with slightly higher temperature.
3. Can tolerate O₂ variations in water.
4. Can be transported from one place to other easily.
5. They are highly nutritive and palatable.

Question 61.
What are the external factors affecting fish culture?
Answer:
External factors affecting fish culture. The factors that affect fish culture are temperature, light rain, water, flood, water current, turbidity of water, pH hardness, salinity and dissolved O₂. Light and temperature also play an important role in fish breeding.

Question 62.
What is Natural breeding of fishes?
Answer:
Natural breeding (Bundh breeding):
These are special types of ponds where natural riverine conditions or any natural water resources are managed for breeding of culturable fishes. These bundhs are constructed in large low-lying areas that can accommodate large quantity of rain water. The shallow area of such bundhs is used as spawning ground.

Question 63.
What are the advantages of composite fish farming?
Answer:
The advantages include:-

1. All available niches are fully utilized.
2. Compatible species do not harm each other.
3. No competition among different species is found.
4. Catla catla, Labeo rohita and Cirrhinus mrigala (surface feeder) are the commonly used fish species for composite fish farming.

Question 64.
What are exotic fishes?
Answer:
Exotic fishes. The fishes imported into a country for fish culture are called exotic fishes and such fish culture is known as exotic fish culture. Examples of such exotic fishes introduced in India are Cyprinus carpio and Oreochromis mossambicus.

Question 65.
What are the types of Prawn fishery?
Answer:
Types of prawn fishery

1. Shallow water prawn fishery – located on the west coast restricted to shallow waters.
2. Estuaries and back waters or saline lake prawn fishery – The area of production of prawns are the back waters seen along the Western coast, Ennur, Pulicat, Chilka lake and Estuaries of Ganga and Brahmaputra rivers.
3. Freshwater prawn fishery – Prawns are caught from the rivers and lakes throughout India.
4. Marine prawn fishery – Most of the marine prawns are caught along the Indian coast belonging to the .family Penaeidae.

Question 66.
What are species of Prawn distributed in water bodies?
Answer:
Species of prawn:
A number of species of prawn are distributed in water resources such as Penaeus indicus, Penaeus monodon, Metapenaeus dobsoni and Macrobrachium rosenbergii.

Question 67.
Name the genus that produces high quality pearls?
Answer:
Pinctada.

Question 68.
How is pearl formed?
Answer:
Pearl Formation:
When a foreign particle accidently enters into the space between mantle and shell of the oyster, it adheres to the mantle. The mantle epithelium encloses it like a sac and starts to secrete concentric layers of nacre around it as a defensive mechanism.

Nacre is secreted continuously by the epithelial layer of the mantle and is deposited around the foreign particle and over a period time the formation of repeated layers of calcium carbonate makes the hard and glossy pearl. When the pearl enlarges the oyster dies. The shell is then carefully opened and the pearls are manually separated and graded.

Question 69.
What are the steps of insertion of nucleus into oyster?
Answer:
Following steps are taken for the insertion of nucleus:-

a. Fitness of oyster for operation:
The selected oysters for the insertion of nucleus should be healthy and strong enough to overcome the stress during operation.

b. Preparation of graft tissues:
The piece of tissue which is inserted inside the mantle is called as ‘GRAFT’ tissue. The outer edges of these graft squares must be known because nacre secreting cells are found only on the outer surface of the mantle so it is essential to keep the outer surface in contact with the inserted nucleus.

c. Preparation of nucleus:
Any small particle may function as nucleus to initiate the pearl formation but it is reported that calcareous nucleus is the best because the deposition of nacre was found to be more on calcarious nucleus.

d. Insertion of nucleus:
For the insertion of nucleus, oysters are fixed in a desk clamp in the position of right valve facing upward. Mantle folds are smoothly touched to expose the foot and the main body mass, followed by an incision into the epithelium of the foot and a slender channel into the main mass one graft tissue which functions as a bed for the nucleus.

e. Post operation care:
Nucleated oysters are placed into cages and suspended into sea water and attached with floating rafts to a depth of 2 to 3 metres for about 6 to 7 days to recover from the shocks due to operation. This period of 6 to 7 days is known as ‘Recovery period’. About 3000 to 3600 nucleated oysters are kept in different cages suspended in sea water at 2 to 3 meters depth for 3 to 6 years and undisturbed except at the time of clearing and inspection.

f. Harvesting of pearl:
Pearls are harvested in the month of December to February which may slightly vary according to climatic conditions. After the completion of 3 years of the insertion of nucleus, pearl oysters are harvested from the sea and the pearls are taken out from the shell.

g. Clearing of pearls:
After taking out the pearls from the oysters shell they are washed properly, cleared with the soap solution.

Question 70.
What is the composition of pearl?
Answer:
Composition of pearl:
Pearl comprises of water, organic matter, calcium carbonate and the residue.

1. Water: 2-4%
2. Organic matter: 3.5-5.9%
3. Calcium carbonate: 90% and
4. Residue: 0.1-0.8% carbonate: 90%

Question 71.
What is Animal husbandry?
Answer:
Animal husbandry is the practice of breeding and raising livestock cattles like cows, buffaloes, and goats and birds etc. that are useful to human beings.

Question 72.
What are the objectives of animal breeding?
Answer:
Objectives of Animal breeding

1. To improve growth rate.
2. Enhancing the production of milk, meat, eggs etc.,
3. Increasing the quality of the animal products.
4. Improved resistance to diseases.
5. Increased reproductive rate.

Question 73.
What are the methods of animal breeding?
Answer:
Methods of Animal breeding:
There are two methods of animal breeding, namely inbreeding and outbreeding:

1. Inbreeding:
Breeding between animals of the same breed for 4-6 generations is called inbreeding. Inbreeding increases homozygosity and exposes the harmful recessive genes.

Continuous inbreeding reduces fertility and even productivity, resulting in “inbreeding depression”. This can be avoided by breeding selected animals of the breeding population and they should be mated with superior animals of the same breed but unrelated to the breeding population. It helps to restore fertility and yield.

2. Outbreeding:
The breeding between unrelated animals is called outbreeding. Individuals produced do not have common ancestors for 4-6 generations.

Outbreeding helps to produce new and favourable traits, to produce hybrids, with superior qualities and helps to create new breeds. New and favourable genes can be introduced into a population through outbreeding.

Question 74.
What is Out crossing?
Answer:
Out crossing:
It is the breeding between unrelated animals of the same breed but having no common ancestry. The offspring of such a cross is called outcross. This method is suitable for breeding animals below average in productivity.

Question 75.
What is Cross breeding?
Answer:
Cross breeding:
Breeding between a superior male of one breed with a superior female of another breed. The cross bred progeny has superior traits (hybrid vigour or heterosis.).

Question 76.
What is Interspecific hybridization?
Answer:
Interspecific hybridization. In this method of breeding mating is between male and female of two different species. The progeny obtained from such crosses are different from their parents, and may possess the desirable traits of the parents.

Question 77.
What is Artificial insemination?
Answer:
Artificial insemination. Artificial insemination is a technique in which the semen collected from the male is injected to the reproductive tract of the selected female.

Question 78.
Explain the Multiple Ovulation Embryo Transfer (MOET)?
Answer:
Multiple ovulation embryo transfer technology (MOET). It is another method of propagation of animals with desirable traits. This method is applied when the success rate of crossing is low even after artificial insemination. In this method Follicle stimulating hormone (FSH) is administered to cows for inducing follicular maturation and super ovulation. Instead of one egg per cycle, 6-8 eggs can be produced by this technology.

The eggs are carefully recovered non-surgically from the genetic mother and fertilized artificially. The embryos at 8-32 celled stages are recovered and transferred to a surrogate mother. For another round of ovulation, the same genetic mother is utilized. This technology can be applied to cattle, sheep and buffaloes. Advantage of this technology is to produce high milk yielding females and high-quality meat yielding bulls in a short time.

Question 79.
What is Dairying and Dairy Operation?
Answer:
Dairying is the production and marketing of milk and its products. Dairy operation consists of proper maintenance of cattle, the collection and processing of milk and its by-products.

Question 80.
What are the groups of cattle?
Answer:
(I) Dairy breeds or Milch breeds:
They are high milk yielders with extended lactation. Eg., Sindhi, Gir, Sahiwal, Jersy, Brown Swiss, Holstein cattle.

(II) Draught purpose breeds:
Bullocks are good for draught purpose. Eg. Kangayam, Malvi.

(III) Dual Purpose breeds:
Cows are meant for yielding more milk and bullocks are used for better drought purpose Eg. Ongole, Hariana.

Question 81.
Distinguish between a healthy cattle and ill cattle?
Answer:

Question 82.
Name the main diseases of dairy cattle?
Answer:
Rinderpest, foot and mouth disease, cow pox, hemorrhagic fever, anthrax.

Question 83.
Write a note on milk products?
Answer:
Milk products:
Milk is produced by dairy animals which is an emulsion of fat and lactose. Milk also contains enzymes which are destroyed during pasteurization.

Milk is a rich source of vitamin A, B„ Bp and deficient in Vitamin C. Due to its high nutrition value, it serves as a . complete food for infants. Dairy products such as yoghurt, cheese, butter, ice cream, condensed milk, curd, and milk powder processed from milk make dairy, a highly farming attraction.

Question 84.
Write on the nutritive value of meat?
Answer:
Meat:
Meat is rich in protein and also contains many minerals like iron, zinc, vitamins and selenium. It also contains vitamins needed for human diet.

Question 85.
What is Poultry Farming?
Answer:
Poultry Farming refers to the rearing and propagation of avian species such as chicken, ducks, turkeys, geese, quail and guinea fowls.

Question 86.
Write on the chicken breeds of egg layers?
Answer:
Egg layers:
These are farmed mainly for the production of egg.

Leghorn:
This is the most popular commercial breed in India and originated from Italy. They are small, compact with a single comb and wattles with white, brown or black colour. They mature early and begin to lay eggs at the age of 5 or 6 months. Hence these are preferred in commercial farms. They can also thrive well in dry areas.

Chittagong:
It is the breed chiefly found in West Bengal. They are golden or light yellow coloured. The beak is long and yellow in colour. Ear lobes and wattles are small and red in colour. They are good egg layers and are delicious.

Question 87.
W-ite on the Broiler breed?
Answer:
Bioiler type:
These are well known for fast growth and soft quality meat.

White Plymouth rock:
They have white plumage throughout the body. It is commonly used in troiler production. This is an American breed. It is a fast growing breed and well suitable for growing intensively in confined farms.

Question 88.
What are Dual purpose chicken breeds?
Answer:
Dual purpose breeds:
These are for both meat and egg production purpose.

Brahma:
It is a breed popularly known for its massive body having heavy bones, well feathered and proportionate body. Pea comb is one of the important breed characters. It has two common varieties namely, Light Brahma and Dark Brahma.

Question 89.
Write a short note on Game breeds?
Answer:
(I) Game breeds:
Since ancient times, special breed of roosters have been used for the sport of cockfighting.

(II) Aseel:
This breed is white or black in colour. The hens are not good egg layers but are good in incubation of eggs. It is found in all states of India. Aseel is noted for its pugnacity, high stamina, and majestic gait and dogged fighting qualities. Although poor in productivity, this breed is well-known for their meat qualities.

Question 90.
Write a short note on Ornamental chicken breeds?
Answer:
Ornamental breeds:
Ornamental chicken are reared as pets in addition to their use for egg production and meat.

Silkie:
It is a breed of chicken having a typical fluffy plumage, which is said to feel like silk and satin. The breed has numerous additional special characters, such as black skin and bones, blue earlobes, and five toes on each foot, while the majority chickens only have four. They are exhibited in poultry .shows, and come out in various colours. Silkies are well recognized for their calm, friendly temperament. Silkie chicken is especially simple to maintain as pets.

Question 91.
What are the types of Poultry farming?
Answer:
Types of Poultry farming:
There are different methods used to rear both broiler and layer chicken. The types of poultry farming are Free range farming, Organic method, Yarding method, Battery cage method and Furnished cage method. Among these, Battery cage method is widely used in large scale poultry farms. The Free range, Organic and Yarding methods are eco-friendly and the eggs produced by such farming practices are preferred in the market.

Question 92.
What are the stages involved in rearing of chicken?
Answer:
Stages involved in rearing:
There are some steps involved in rearing of chicken:-

1. Selection of the best layer:
An active intelligent looking bird, with a bright comb, not obese should be selected.

2. Selection of eggs for hatching: Eggs should be selected very carefully. Eggs should be fertile, medium sized, dark brown shelled and freshly laid eggs are preferred for rearing. Eggs should be washed, cleaned and dried.

3. Incubation and hatching:
The maintenance of newly laid eggs in optimum condition till hatching is called incubation. The fully developed chick emerges out of egg after an incubation period of 21 – 22 days.

There are two types of incubation namely natural incubation and artificial incubation. In the natural incubation method, only a limited number of eggs can be incubated by a mother hen. In artificial incubation, more number of eggs can be incubated in a chamber (Incubator).

3. Brooding:
Caring and management of young chicks for 4 – 6 weeks immediately after hatching is called brooding. It can also be categorized into two types namely natural and artificial brooding.

4. Housing of Poultry:
To protect the poultry from sun, rain and predators, it is necessary to provide housing to poultry. Poultry house should be moisture-proof, rat proof and it should be easily cleanable and durable.

5. Poultry feeding:
The diet of chicks should contain adequate amount of water, carbohydrates, proteins, fats, vitamins and minerals.

Question 93.
What are poultry products?
Answer:
Eggs and meat.

Question 94.
What are poultry byproducts?
Answer:
A number of poultry byproducts like blood-meal, feather meal, poultry byproduct meal and hatchery by-product meal are used as good sources of nutrients for meat producing animals and poultry. These byproducts supply proteins, fats, vitamins and good amount of minerals.

Question 95.
Name Poultry diseases?
Answer:
Poultry diseases:
Ranikhet, Coccidiosis and Fowl pox are some common poultry diseases.

Question 96.
What are the benefits of Poultry farming?
Answer:
Benefits of Poultry farming are:

1. It does not require high capital for construction and maintenance of the poultry farming.
2. It does not require a big space.
3. It ensures high return of investment within a very short period of time.
4. It provides fresh and nutritious food and has a huge global demand.
5. It provides employment opportunities for the people.

Question 97.
What are the native and exotic duck breeds?
Answer:

1. Native Breeds – Indian Runner, Syhlet meta.
2. Exotic Breeds – Muscori, Pekin, Aylesbury, Campbell.

Question 98.
What are the types of duck breeds?
Answer:
There are three types of ducks depending on the purpose for which it is formed. They are meat productive duck breeds, egg productive duck breeds, and breeds for both meat and egg production.

Question 99.
What are the advantages of duck farming?
Answer:
Advantages of duck farming:
They can be reared in small backyards where water is available and needs less care and management as they are very hardy. They can adapt themselves to all types of environmental conditions and are bred for feed efficiency, growth rate and resistance to diseases.

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Textbook Evaluation Solved
Choose The Correct Answer
Question 1.
The maintenance of constant internal environment is referred as .
(a) Regulation
(b) Homeostasis
(c) Co-ordination
(d) Hormonal control
Answer:
(b) Homeostasis

Question 2.
Which of the following are exclusive endocrine glands?
(a) Thymus and testis
(b) Adrenal and ovary
(c) Parathyroid and adrenal
(d) Pancreas and parathyroid
Answer:
(c) Parathyroid and adrenal

Question 3.
Which of the following hormone is not secreted under the influence of pituitary gland?
(a) Thyroxine
(b) Insulin
(c) Oestrogen
(d) Glucocorticoids
Answer:
(A) Insulin

Question 4.
Spermatogenesis in mammalian testes is controlled by?
(a) Luteinising hormone
(b) Follicle stimulating hormone
(c) FSH and prolactin
(d) GH and prolactin
Answer:
(A) Follicle stimulating hormone

Question 5.
Serum calcium level is regulated by?
(a) Thyroxine
(b) FSH
(c) Pancreas Assertion is true, but Reason is false
(d) Thyroid and parathyroid
Answer:
(d) Thyroid and parathyroid

Question 6.
Iodised salt is essential to prevent?
(a) Rickets
(b) Scurvy
(c) Goitre
(d) Acromegaly
Answer:
(c) Goitre

Question 7.
Which of the following gland is related with immunity?
(a) Pineal gland
(b) Adrenal gland
(c) Thymus
(d) Parathyroid gland
Answer:
(c) Thymus

Question 8.
Which of the following statement about sex hormones is correct?
(a) Testosterone is produced by Leydig cells under the influence of luteinizing hormone
(b) Progesterone is secreted by corpus luteum and softens pelvic ligaments during child birth
(c) Oestrogen is secreted by both sertoli cells and corpus luteum
(d) Progesterone produced by corpus luteum is biologically different from the one produced by placenta.
Answer:
(a) Testosterone is produced by Leydig cells under the influence of luteinizing hormone

Question 9.
Hypersecretion of GH in children leads to
(a) Cretinism
(b) Gigantism
(c) Graves disease
(d) Tetany
Answer:
(b) Gigantism

Question 10.
A pregnant female delivers a baby who suffers from stunted growth, mental retardation, low intelligence quotient and abnormal skin.This is the result of …………….
(a) Low secretion of growth hormone
(b) Cancer of the thyroid gland
(c) Over secretion of pars distalis
(d) Deficiency of iodine in diet.
Answer:
(b) Cancer of the thyroid gland

Question 11.
The structure which connects the hypothalamus with anterior lobe of pituitary gland is the
(a) Dendrites of neuro hypophysis
(b) Axons of neurohypophysis
(c) Bands of white fibers from cerebellar region
(d) Hypophysial portal system
Answer:
(b) Axons of neurohypophysis

Question 12.
Comment on homeostasis?
Answer:
Homeostasis: Maintenance of constant internal environment of the body by the different coordinating system. ‘

Question 13.
Which one of the following statement is correct
(a) Calcitonin and thymosin are thyroid hormones
(b) Pepsin and prolactin are selected in stomach
(c) Secretin and rhodopsin are polypeptide hormones
(d) Cortisol and aldosterone are steroid hormones
Answer:
(d) Cortisol and aldosterone are steroid hormones .

Question 14.
Which of the given option shows all wrong statement for thyroid gland Statements
(i) It inhibits process of RBC formation
(ii) It hepls in maintenance of water and electrolytes
(iii) Its more secretion can reduce blood pressure
(iv) It stimulates osteoblast
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (i) and (iii)
Answer:
(c) (i) and (iv)

Question 15.
Hormones are known as chemical messenger? Justify?
Answer:
Hormones are released into the blood stream and circulated as chemical signals. These act specifically on certain organs or tissues called target organs or tissues. These speed up or slow down or alter the activity of target tissues or organs. Hence they are known as chemaical messengers.

Question 16.
Write the role of oestrogen in ovulation?
Answer:
Oestrogen is the ovarian hormone secreted during the proliferation phase of menstrual cycle from the 6th day to 14th day of the cycle. On 14th day of the cycle, under the influence of uteinizing hormone, ovum is released from the graffian follicles. This process is known as ovulation.

Question 17.
Comment on Acini of thyroid gland?
Answer:
Thyroid gland is a bilobed endocrine gland. Each lobe is made up of many lobules. The lobules consist of follicles called acini. Each acinus is lined with glandular, cuboidal or squamous epithelial cells. The lumen of acinus is filled with colloid, a thick glycoprotein mixture consisting of thyroglobulin molecules.

Question 18.
Write the causes for diabetes mellitus and diabetes insipids?
Answer:
Diabetes mellitus is caused due to reduced secretion of insulin. As a result, blood glucose level is elevated. Diabetes insipidus is caused due to under secretion of ADH or vasopression. As a result, reabsorption of water gets affected and hende large amount of urine is produced.

Question 19.
Specify the symptoms of acromegaly?
Answer:
Acromegaly is caused due to excessive secretion of growth hormone in adults. The symptoms of acromegaly are overgrowth of hand bones, feet bones, jaw bones malfunctioning of gonads. enlargement of viscera, tongue, lungs, heart, liver, splean and endocrine glands like thyroid, or adrenal glands.

Question 20.
Write the symptoms of cretinism?
Answer:
Cretinism is caused due to hypothyroidism in infants. A cretin child shows the following symptoms:-

1. Retarded skeletal growth.
2. Absence of sexual maturity
3. Retarded mental ability
4. Thick and short limbs
5. Thick wrinkled skin
6. Bloated face
7. Protruded enlarged tongue
8. Low BMR, slow pulse rate,subnormal body temperature and elevated blood cholesterol levels

Question 21.
Briefly explain the structure of thyroid gland?
Answer:
The thyroid gland is butterfly shaped, bilobed situated below the larynx on each side of the upper trachea. The two lobes are connected by a median tissue mass called isthmus. Each lobe is made up of many lobules. The lobules consist of follicles called acini. Each acinus is lined with glandular, cuboidal or squamous epithelial cells.

The lumen of acini is filled with colloid, a thick glycoprotein mixture consisting of thyroglobulin molecules. The thyroid gland secretes Tri-iodothyronine (T,) and tetra-iodothyronine (T4) or thyroxine hormones. These are concerned with metabolism.

Question 22.
Name the layers of adrenal cortex and mention their secretions?
Answer:
A pair of adrenal glands are located at the anterior end of the kidneys. Elence, they are called suprarenal glands.The outer region is called cortex and the inner region is medulla. The adrenal cortex has three distinct zones,

1. Zona Glomerulosa
2. Zona fasciculata
3. Zona reticularis

1. Zona Glomerulosa:

• It is the outer thin layer. It constitutes about 15% of the cortex.
• It secretes mineralocorticoids.

2. Zona fasciculata:

• It is the middle wide layer constituting about 15% of adrenal cortex.
• It secretes glucocorticoids such as cortisol, corticosterone and trace amounts of adrenal androgen and oestrogen.

3. Zona reticularis:

• It is the inner zone of adrenal cortex.
• It constitutes about 10% of adrenal cortex.
• It constitutes about 10% of adrenal cortex.
• It secretes the adrenal androgen, trace amount of oestrogen and glucocorticoids.

Question 23.
Differentiate hyperglycemia from hypoglycemia?
Answer:

Question 24.
Write the functions of CCK?
Answer:
CholecystokininCholecystokinin is secreted by duodenum in response to the presence of fat and acid in the diet. It acts on the gall bladder to release bile into duodenum and stimulates the secretion of pancreatic enzymes and its discharge.

Question 25.
Growth hormone is important for normal growth. Justify the statement?
Answer:
Growth hormone promotes growth of all the tissues and metabolic process of the body. It influences the metabolism of carbohydrate, proteins and lipids. It increases the rate of protein biosynthesis in the cells.

It stimulates chondrogenesis (cartilage formation), osteogenesis (bone formation) and helps in the retention of minerals like nitrogen, potassium, phosphorus, sodium etc in the body. It increases the release of fatty acid from adipose tissue and decreases the rate of glucose utilization for energy by the cells. The hyposecretion of growth hormones causes dwarfism in children.

Question 26.
Pineal gland is an endocrine gland, write its role?
Answer:
The pineal gland or epiphysis cerebri or conarium is located behind the third ventricle of brain. It is formed of paranchymal cells and interstitial cells. It secretes the hormone, melatonin.

It plays a central role in the regulation of circadian rhythm of our body and maintains normal sleep wake cycle. It also regulates the timing of sexual maturation of gonads. It also influences metabolism, pigmentation, menstrual cycle and defence mechanism of our body.

Question 27.
Comment on the functions of adrenalin?
Answer:
Adrenalin increases liver glycogen breakdown into glucose and increases the release of fatty acids from fat cells. During emergency, it increases heart beat rate and blood pressure.lt stimulates the smooth muscles of cutaneous and visceral arteries to decrease blood flow. It increases blood flow to the skeletal muscles and nervous tissue.

Question 28.
Predict the effects of removal of pancreas from the human body?
Answer:
Pancreas is both exocrine and endocrine gland. It is located just below the stomach as a leaf like structure. It secretes digestive enzymes and hormones like insulin and glucogon.

The digestive enzymes digest carbohydrates, proteins and fats. Insulin and glucose regulate blood sugar level. If pancreas is removed from the body, digestion and main’taince of blood sugar level gets afftected.

Question 29.
Enumerate the role of kidney as an endocrine gland?
Answer:
Kidney has endocrine tissues which act as partial endocrine gland. It secretes renin, erythropoietin and calcitripl. Renin is secreted by juxta glomerular cells. It increases blood pressure when angiotensin is formed in blood.

Erythropoietin is also secreted by the juxta glomerular cells of the kidney and stimulates erythropoieis in bone marrow. Calcitriol is secreted by proximal tubes of nephrons. It is an active form of vitamin D3 which promotes calcium and phosphorus absorption from intestine and accelerates bone formation.

Question 30.
Write a detailed account of gastro intestinal tract hormones?
Answer:
Group of specialized endocrine cells present in gastro-intestial tract secretes hormones such as gastrin, cholecystokinin (CCK), secretin and gastric inhibitory peptides (GIP). Gastrin acts on the gastric glands and stimulates the secretion of HC1 and pepsinogen.

Cholecystokinin (CCK) is secreted by duodenum in response to the presence of fat and acid in the diet. It acts on the gall bladder to release bile into duodenum and stimulates the secretion of pancreatic enzymes and its discharge. Secretin acts on acini cells of pancreas to secrete bicarbonate ions and water to neutralize the acidity. Gastric inhibitory peptide (GIP) inhibits gastric secretion and motility.

In Text Questions Solved

Question 1.
Pituitary gland is located in a depression in the sphenoid bone of skull below the brain, so is also called hypothalamus cerebri. Discuss the following:
(a) Pituitary gland is commonly called “master gland” of the body?
(b) Discuss the role of hypothalamus and pituitary as a coordinated unit in maintaining physiological processes?
(c) How does the posterior lobe of pituitary help in osmoregulation?
Answer:
(a) Pituitary gland is commonly called “master gland” of the body because it regulates the activity of other endocrine glands such as adrenal gland, thyroid gland, testis and ovary.

(b) The hypothalamus sends signals to the pituitary gland to release or inhibit pituitary hormone releasing factor production thus maintaining Homeostasis of the body.

(c) The posterior lobe of pituitary helps in osmoregulation by secreting the hormones namely vasopressin and oxytocin which increases tubular reabsorption of water in the nephrons.

Question 2.
Endocrine glands control and coordinate the body functions through secreting certain chemical messengers called hormones. Due to certain physiological reasons, the blood glucose level of an otherwise normal person?
(a) Give the possible cause for the increases in blood glucose level?
(b) What is the chemical nature of this hormone? Discuss its role in the body?
(c) How can this condition be reversed?
Answer:
(a) Stress and anxiety could have been the possible causes for the sudden increase in blood glucose level.

(b) Insulin is a polypeptide hormone. Insulin is secreted by the Islets of Langerhans of pancreas. It helps in converting glucose into glycogen or fat and allowing-oxidation of glucose inside the cells. Thus, insulin helps maintain the blood sugar level.

(c) This condition can be reversed by relaxing and taking a walk.

Question 3.
Identify the peaks of FSH, LH, Oestrogen and Progesterone hormones through out the menstrual cycle?
Answer:

Oestrogen, FSH are in the peak during the follicular phase (6 -13 days) of menstruation. LH is at the peak during ovulation that is on the 14th day of menstrual cycle. Progesterone is at the peak in the luteal phase of menstruation (14 – 28 days).

Samacheer Kalvi 11th Bio Zoology Chemical Coordination and Integration Additional Questions & Answers

I. Choose The Correct Answer

Question 1.
Which of the following is not related to hormones?
(a) They are secreted by ductless glands
(b) They act on the target
(c) They act as chemical messengers
(d) They play an important role in disgestion
Answer:
(d) They play an important role in disgestion

Question 2.
Which of the following is a partial endocrine?
(a) Thymus gland
(b) Pineal gland
(c) Gonads
(d) Parathyroid gland
Answer:
(c) Gonads

Question 3.
Which of the following is the function of Growth Hormone?
(a) It increases blood pressure
(b) It influences the metabolism of carbohydrates, proteins and lipids
(c) It stimulates melanin synthesis in melanocytes
(d) It promotes reabsorption of water by nephrons
Answer:
(b) It influences the metabolism of carbohydrates, proteins and lipids

Question 4.
Which of the following stimulates milk secretion after the child birth in females?
(a) Luteotropic hormone
(b) Luteinizing hormone
(c) Follicle stimulating hormone
(d) Somatotropin
Answer:
(a) Luteotropic hormone

Question 5.
Which of the following is the reason for calling vasopressin as the anti Jiuretic hormone?
(a) It promotes dilution of urine
(b) It reduces dilution of urine
(c) It increases blood pressure
(d) It constricts blood vessels
Answer:
(b) It reduces dilution of urine

Question 6.
A person is unable to sleep normally. He may not get proper secretion of?
(a) Thyroxine
(b) Vasopression
(c) Melatonin
(d) Oxytocin
Answer:
(c) Melatonin

Question 7.
Why is parathormone called hypercalcemic hormone?
(a) It decreases blood calcium level
(b) It increases blood potassium level
(c) It increases blood calcium level
(d) It decreases blood potassium level
Answer:
(b) It increases blood potassium level

Question 8.
Which of the following is not the function of cortisol?
(a) It produces anti inflammatory reactions
(b) It stimulates RBC production
(c) It supresses the immune response
(d) It regulates water and electrolyte balance of the body
Answer:
(d) It regulates water and electrolyte balance of the body

Question 9.
Which adrenal hormone is concerned with maintaining electrolytes, osmotic pressure and blood pressure?
(a) Cortisol
(b) Glucocorticoids
(c) Aldosterone
(d) Adrenalin
Answer:
(c) Aldosterone

Question 10.
Which of the following hormones prepares the body for meeting emergency situations?
(a) Aderenalin and noradrenalin
(b) Glucocorticoids and mineralocorticoids
(c) Cortisol and Aldosterone
(d) Glucocorticoids and corticosterone
Answer:
(a) Aderenalin and noradrenalin

Question 11.
Which of the following is the function of insulin?
(a) It promotes Glycogenolysis
(b) It increases the uptake of glucose into the body cells
(c) It promotes gluconeogenesis
(d) It reduces the cellular uptake and utilization of glucose
Answer:
(b) It increases the uptake of glucose into the body cells

Question 12.
Which of the following is the functiion of Glucogon?
(a) It increases the cellular utilization of glycogen into glucose
(b) It promotes the breakdown of glycogen into glucose
(c) It inhibits the breakdown of glycogen into glucose
(d) It inhibits the production of glucose from non-carbohydrate sources
Answer:
(b) It promotes the breakdown of glycogen into glucose

Question 13.
Which of the following promotes the appearance of secondary sexual characters in male and female respectively?
(a) Testosterone and progesterone
(b) Progesterone and testosterone
(c) Testosterone and oestrogen
(d) Oestrogen and testosterone
Answer:
(c) Testosterone and oestrogen

Question 14.
Which of the following is not the function of progesterone?
(a) Implantation of zygote in the uterus
(b) Decreasing the contraction of uterus
(c) Formation of placenta
(d) Maturation of reproductive organs
Answer:
(d) Maturation of reproductive organs

Question 15.
Which of the following hormone is secreted by proximal tubules of nephron?
(a) Renin
(b) Calcitriol
(c) Erythropoietin
(d) Cholecystokinin
Answer:
(b) Calcitriol

Question 16.
A person attains a maximum of 4 feet height. What could be the reason for this?
(a) Hypersecretion of somatotropic hormone
(b) Hypersecretion of ACTH
(c) Hyposecretion of TSH
(d) Hyposecretion of somatotropic hormone
Answer:
(d) Hyposecretion of somatotropic hormone

Question 17.
An excessive secretion of growth hormone in adults lead to ……………….
(a) Gigantism
(b) Dwarfism
(c) Acromegaly
(d) Cretinism
Answer:
(c) Acromegaly

Question 18.
Why does cretenism occur?
(a) Hypothyroidism in adults
(b) Hypothyroidism in infants
(c) Hyperthroidism in adults
(d) lower level of iodine in blood
Answer:
(b) Hypothyroidism in infants

Question 19.
Increased heartbeat, high BP and protrusion of eyeball are the characteristics of …………….
(a) Endemic goitre
(b) Tetany
(c) Myxodema
(d) Grave’s disease
Answer:
(d) Grave’s disease

Question 20.
Hypocalcemia occures due to?
(a) Hypersecretion of parathyroid hormone
(b) Hyposecretion of parathyroid hormone
(c) Hypersecretion of cortisol
(d) Hyposecretion of cortisol
Answer:
(b) Hyposecretion of parathyroid hormone

Question 21.
Demineralization occurs due to?
(a) Hypoparathyroidism
(b) Hypothyroidism
(c) Hyperthyroidism
(d) Hyperparathyroidism
Answer:
(d) Hyperparathyroidism

Question 22.
Hyper pigmentation of skin and low metabolic rate are the symptoms of …………………..
(a) Cushing’s syndrome
(b) Addison’s disease
(c) Grave’s disease
(d) Gull’s disease
Answer:
(b) Addison’s disease

Question 23.
Excess secretion of cortisol leads to
(a) Addison’s disease
(b) Grave’s disease
(c) Cushing’s syndrome
(d) Gull’s diesease
Answer:
(c) Cushing’s syndrome

Question 24.
In Type I diabetes ………………
(a) Insulin is produced in sufficient quantity
(b) Insulin resistance occurs
(c) Insulin is produced more
(d) Insulin is not produced
Answer:
(d) Insulin is not produced

Question 25.
Excessive intake of food in diabetes is called as …………………..
(a) Polydipsia
(b) Polyurea
(c) Polyphagia
(d) Ketosis
Answer:
(c) Polyphagia

Question 26.
The hyposecretion of vasopressin results in …………….. ?
(a) Diabetes mellitus
(b) Diabetes insipidus
(c) Ketosis
(d) Hyperglycemia
Answer:
(b) Diabetes insipidus

Question 27.
What does peptide hormone do as it cannot cross the phospholipid cell membrane?
(a) It combines with cAMP
(b) It binds to the receptors on the exterior cell surface
(c) It combines with steroids
(d) It combines with adenylate cyclases
Answer:
(a) It binds to the receptors on the exterior cell surface

Question 28.
In case of steroids hormones, dimer of receptor-hormone complex is formed. What does it do then?
(a) It binds with golgi complex
(b) It binds with tRNA
(c) It binds with mRNA
(d) It binds with DNA
Answer:
(d) It binds with DNA

II. Fill in the Blanks

Question 1.
The hormones are converted into inactive compounds by the …………………….. and excreted by the ……………………..
Answer:
(liver, kidneys )

Question 2.
Hormones act as …………………….. to perform specific functions in the target organs.
Answer:
( organic catalysts / coenzymes )

Question 3.
The pituitary gland is controlled by the ……………………..
Answer:
(hypothalamus)

Question 4.
Hypothalamus produces …………………….. which regulate the secretions of the pituitary gland.
Answer:
(neurotransmitters)

Question 5.
The pituitary gland is located in the bony cavity of the sphenoid bone called ……………………..
Answer:
( sella turcica)

Question 6.
The pituitary gland is connected to the hypothalamus by a stalk called ……………………..
Answer:
(infundibulum)

Question 7.
The anterior lobe of the pituitary gland originates from the embriyonic invagination of pharyngeal epithelium called ……………………..
Answer:
(Rathke’s pouch)

Question 8.
…………………….. decreases the rate of glucose
Answer:
(Growth Hormone)

Question 9.
ACT4 stimulates melanin synthesis in ……………………..
Answer:
(Melanocytes)

Question 10.
LH is also known as ……………………..
Answer:
(Interstitial cell stimulating Hormone)

Question 11.
FSH and LH are collectively referred as ……………………..
Answer:
(gonadotropins)

Question 12.
High prolactin secretion during lactation supresses LH secretion and ……………………..
Answer:
(ovulation)

Question 13.
…………………….. promotes reabsorption of water and electrolytes by distal tubules of nephron.
Answer:
(ADH / vasopressin )

Question 14.
…………………….. stimulates ejection of milk from the mammary glands.
Answer:
(oxytocin)

Question 15.
The pineal gland secretes …………………….. which plays a central role in the regulation of circadian rhythm of our body.
Answer:
(melatonin)

Question 16.
The two lateral lobes of thyroid gland are connectd by a median tissue mass called ……………………..
Answer:
(isthmus)

Question 17.
…………………….. gland produces ‘T’ lymphocytes which provides cell mediated immunity.
Answer:
(Thymus)

Question 18.
…………………….. produces anti inflammatory reactions and suppresses the immune response.
Answer:
(cortisol)

Question 19.
…………………….. increases the breakdown of liver glycogen into glucose
Answer:
(Adrenalin)

Question 20.
Both adrenalin and nor adrenalin are ……………………..
Answer:
(catecholamines)

Question 21.
…………………….. stimulates the reabsorption of sodium and water.
Answer:
(Aldosterone)

Question 22.
The beta cells of islets of langerhans secrete ……………………..
Answer:
(Insulin)

Question 23.
The alpha cells of islets of langerhans secrete ……………………..
Answer:
(glucagon)

Question 24.
The delta cells of islets of langerhans secrete ……………………..
Answer:
(somatostatin)

Question 25.
Insulin inhibits the breakdown of …………………….. into glucose.
Answer:
(glycogen)

Question 26.
…………………….. is called a hypoglycemic hormone.
Answer:
(Insulin)

Question 27.
…………………….. promotes the breakdown of glycogen into glucose.
Answer:
(Glucogon)

Question 28.
The breakdown of glucose is called ……………………..
Answer:
(glycogenolysis)

Question 29.
The synthesis of glucose from non – carbohydrate molecules is called ……………………..
Answer:
(gluconeolysis)

Question 30.
…………………….. reduces the cellular update and utilization of glucose.
Answer:
(Glugocon)

Question 31.
…………………….. is called a hyperglycemic hormone.
Answer:
(Glucogon)

Question 32.
The …………………….. cells of testes secrete male sex hormone.
Answer:
(Leydig)

Question 33.
…………………….. is reposible for development of secondary sexual charactes of female.
Answer:
(Oestrogen)

Question 34.
…………………….. prepares the uterus for implantation of the fertilized ovum.
Answer:
(Progesterone)

Question 35.
…………………….. on the atrial wall secretes atrial natriuretic factor to reduce the blood pressure .
Answer:
(cardiocytes)

Question 36.
…………………….. increases blood pressure when angiotension is formed in blood.
Answer:
(Renin)

Question 37.
stimulates the erythyropoiesis in bone marrow.
Answer:
(Erythropoietin)

Question 38.
…………………….. is the hormone secreted by proximal tubules of nephron which promotes calcium and phosphorus absorption from intestine.
Answer:
(Calcitriol)

Question 39.
…………………….. stimulates the secretion of HCl and pepsinogen.
Answer:
(Gastrin)

Question 40.
…………………….. stimulates the release of bile into duodenum and secretion of panereatic enzymes.
Answer:
(Cholecystokinin)

Question 41.
…………………….. acts on acini cells of pancreas to secrete bicarbonate ions and water to neutralise the acidity.
Answer:
(secretin)

Question 42.
…………………….. is caused due to hyposecretion of growth hormone in children.
Answer:
(dwarfism)

Question 43.
…………………….. is caused due to hypersecretion of growth hormone in childre.
Answer:
(Gigantism)

Question 44.
…………………….. is caused due to excessive secretion of growth hormone in adults.
Answer:
(Acromegaly)

Question 45.
The hypothyroidism in children causes ……………………..
Answer:
(cretinism)

Question 46.
The hyposecretion of thyriod in adults causes ……………………..
Answer:
(Myxodema)

Question 47.
Myxodema is otherwise called ……………………..
Answer:
(Gull’s disease)

Question 48.
The hypersecretion of thyriod gland causes as ……………………..
Answer:
(exopthalmic goitre)

Question 49.
The hyposecretion of parathyroid hormone causes ……………………..
Answer:
(Tetany)

Question 50.
The exophthalmic goitre is called as ……………………..
Answer:
(Grave’s disease / thyrotoxicosis)

Question 51.
Due to hyposecretion of parathyroid hormone serum …………………….. level decreases.
Answer:
(calcium)

Question 52.
Demineralisation is caused due to ……………………..
Answer:
(hyperparathyroidism)

Question 53.
…………………….. is caused due to hyposecretion of glucocorticoids and mineralocorticoids from the adrenal cortex.
Answer:
(Addison’s disease)

Question 54.
The hypersecretion of cortisol causes ……………………..
Answer:
(Cushing’s syndrome)

Question 55.
Type II diabetes is caused due to ……………………..
Answer:
(insulin resistance)

Question 56.
Type I diabetes is ……………………..
Answer:
(insulin dependent)

III. Answer The Following Questions

Question 1.
Distinguish between Exocrine glands and Endocrine glands?
Answer:

Question 2.
Why is hypothalamus considered as neuro endocrine gland?
Answer:
The hypothalamus alone with its neural function produces hormones. Hence it is considered as neuro-endocrine gland.

Question 3.
What are the functions of hypothalamus?
Answer:
Hypothalamus maintains homeostasis, blood pressure, body temperature, cardio and fluid electrolyte balance of the body. It influences various emotional responses.

Question 4.
Write on the origin of pituitary gland?
Answer:
The anterior lobe of pituitary gland originates from the embryonic invagination of pharyngeal epithelium called Rathke’s pouch. The posterior lobe originates from the base of the brain as an outgrowth of hypothalamus.

Question 5.
What are the lobes of adenohypophysis?
Answer:
Pars distalis, Pars intermedia and Pars tuberalis.

Question 6.
What is Pars nervosa?
Answer:
The neurohypophysis of the pituitary gland is known as pars nervosa.

Question 7.
Name the hormones secreted by the pituitary gland?
Answer:
The anterior lobe of pituitary secretes six tropic hormones such as growth hormone (GH), thyroid stimulating hormone (TSH), adreno corticotropic hormone (ACTH), follicle stimulaiton hormone (FSH), luteinizing hormone (LH), luteotropic hormone (LTH) and melanocyte stimulating hormone (MSH) (in lower animals only). The posterior lobe of pituitary secretes the hormones namely vasopressin and oxytocin.

Question 8.
Write a paragraph on the Growth Hormone?
Answer:
Growth hormone (GH):
It is also known as somatotropic hormone (STH) or Somatotropin. It is a peptide hormone Growth hormone promotes growth of all the tissues and metabolic process of the body. It influences the metabolism of carbohydrates, proteins and lipids and increases the rate of protein biosynthesis in the cells.

It stimulates chondrogenesis (cartilage formation), osteogensis (bone formation) and helps in the retention of minerals like nitrogen, potassium, phosphorus, sodium etc., in the body. GH increases the release of fatty acid from adipose tissue and decreases the rate of glucose utilization for energy by the cells. Thus it conserves glucose for glucose dependent tissues, such as the brain.

Question 9.
Write on the role of Thyroid stimulating hormone and Adreno cortico tropic hormone? Thyroid stimulating hormone (TSH) or thyrotropin?
Answer:
TSH is a glycoprotein hormone, which stimulates the thyroid gland to secrete Triiodothyronine (T₃) and thyroxine (T₄). TSH secretion is regulated by negative feedback machanism. It’s release from the anterior pitutary is induced by the thyrotropin releasing hormone (TRH). When thyroxine level in the blood increases, TRH acts on both the pituitary and hypothalamus to inhibit TSH secretion.

Adreno cortico tropic hormone (ACTH):
ACTH is a peptide hormone that stimulates the adrenal cortex to secrete glucocorticoids and mineralocorticoids. It stimulates melanin synthesis in melanocytes, induces the release of fatty acids from adipose tissues and stimulates insulin secretion. ACTH secretion is regulated by negative feedback mechanism.

Question 10.
What are the functions of follicle stimulation hormone?
Answer:
Follicle stimulating hormone (FSH):
FSH is a glycoprotein hormone which regulates the functions of the gonads (ovary and testis). In males, FSH along with androgens acts on the germinal epithelium of seminiferous tubules and stimulates the production and release of sperms (spermatogenesis). In females, FSH acts on the ovaries and brings about the development and maturation of gratfran follicles.

Question 11.
What is the role of Luteinizing hormone (LH)?
Answer:
Luteinizing Hormone is a glycoprotein hormone which is also known as interstitial cell stimulating hormone (ICSH). In males, ICSH acts on the interstitial cells of testis to produce the male sex hormone, testosterone. In females, LH along with FSH matures the ovarian follicles.

LH independently induces ovulation, maintains the corpus luteum and promotes synthesis and release of ovarian hormones. FSH and LH are collectively referred as gonadotropins. FSH and LH are not produced during childhood. The secretion of FSH and LH starts only during prepubertal period.

Question 12.
What is the significance of Luteotropic hormone (LTH)?
Answer:
Luteo Tropic Hormone is also called luteotropin or lactogenic hormone or prolactin or mammotropin. It is a protein hormone which stimulates milk secretion after the child birth in females. High prolactin secretion during lactation suppresses LH secretion and ovulation since it induces the corpus luteum hence named as luteo tropic hormone.

Question 13.
What are the hormones of neurohypophysis?
Answer:
(i) Vasopressin or antidiuretic hormone (ADH):
ADH is a peptide hormone which promotes reabsorption of water and electrolytes by distal tubules of nephron and thereby reduces loss of water through urine. Hence it is called as anti diuretic hormone. It also causes constriction of blood vessels when released in large amount and increases blood pressure. ADH deficiency causes Diabetes insipidus which induces the production of large amount of urine.

(ii) Oxytocin (means quick birth):
It is a peptide hormone which stimulates vigorous contraction of the smooth muscles of uterus during child birth and ejection of milk from the mammary glands.

Question 14.
What are the functions of pineal gland?
Answer:
In human, the pineal gland or epiphysis cerebri or conarium is located behind the third ventricle of brain and is formed of parenchymal cells and interstitial cells.

It secretes the hormone, melatonin, which plays a central role in the regulation of circadian rhythm of our body and maintains the normal sleep wake cycle. It also regulates the timing of sexual maturation of gonads. In addition melatonin also influences metabolism, pigmentation, menstrual cycle and defence mechanism of our body.

Question 15.
Write on the role of parathyroid gland?
Answer:
In human, four tiny parathyroid glands are found in the posterior wall of the thyroid glands. This galnd is composed of two types of cells, the chief cells and oxyphil cells. The chief cells secrete parathyroid hormone (PTH) and the functions of oxyphil cells are not known. Parathyroid hormone or parathormone (PTH).

PTH is a hypercalcemic hormone. It is a peptide hormone involved in controlling the calcium and phosphate homeostasis. The secretion of PTH is controlled by calcium level in the blood. It increases the blood calcium level by stimulating osteoclasts to dissolve the bone matrix.

As a result calcium and phosphate are released into the blood. PTH enhances the reabsorption of calcium and excretion of phosphates by the renal tubules and promotes activation by vitamin D to increase calcium absorption by intestinal muscosal cells.

Question 16.
Write a paragraph on Thymus gland?
Answer:
Thymus gland is partially an endocrine and partially a lymphoid organ. It is a bilobed structure located just above the heart and aorta, behind the sternum. It is covered by fibrous capsule and anatomically it is divisble into an outer cortex and an inner medulla.

It secretes four hormones such as thymulin, thymosin, thymopoietin and thymic humoral factor (THF). The primary function of thymus is the production of immuno competent ‘T’ lymphocytes which provides cell mediated immunity.

Question 17.
Explain the hormones secreted by Adrenal gland?
Answer:
A pair of adrenal glands are located at the anterior end of the kidneys, hence also called suprarenal glands. Anatomically the outer region is the cortex and the inner region is the medulla.

Histologically the adrenal cortex has three distinct zones, zona glomerulosa, zona fasciculata and zona reticularis. Zona glomerulosa an outer thin layer constitutes about 15% of adrenal cortex, and secretes mineralocorticoids.

Zona fasciculata, the middle widest layer constitutes about 75% of adrenal cortex and secretes glucocorticoids such as cortisol, corticosterone and trace amounts of adrenal androgen and oestrogen. Zona reticularis, an inner zone of adrenal cortex constitute about 10% of adrenal cortex and secretes the adrenal androgen, trace amount of oestrogen and glucocorticoids.

Adrenal medulla:
It is the central part of adrenal gland and is composed of ovoid and columnar cells, which are found around the network of blood capillaries. Adrenalin (epinephrine) and nor adrenalin (nor epinephrine) are the two hormones secreted by the adrenal medulla. Both adrenalin and nor adrenalin are catecholamines.

Function of adrenal hormones:
Glucocorticoids stimulate gluconeogenesis, lipolysis and proteolysis (the life saving avtivity). Cortisol is a glucocorticoid invloved in maintaining cardio vascular and kidney functions.

It produces anti-inflammatory reactions and suppresses the immune response. It stimulates the RBC production. It is also known as stress combat hormone. Mineralocorticoids regulates water and electrolyte balance of our body.

Aldosterone stimulates the reabsorption of sodium and water and eliminates potassium and phosphate ions through excretion,, thus it helps in maintainting electrolytes, osmotic pressure and blood pressure. Adrenal androgen plays a role in hair growth in the axial region, pubis and face during puberty.

The adrenal medulla secretes the hormones adrenalin and noradrenalin and are referred as “3F hormone” (fight, flight and fright hormone). Adrenalin increases liver glycogen breakdown into glucose and increases the release of fatty acids from fat cells.

During emergency it increases heart beat rate and blood pressure. It stimulates the smooth muscles of cutaneous and visceral arteries to decrease blood flow. It increases blood flow to the skeletal muscles therby increases the metabolic rate of skeletal muscles, cardiac muscles and nervous tissue.

Question 18.
What are the hormones responsible for maintaining blood glucose level?
Answer:
Insulin and glucogon are the hormones secreted by Islets of langerhans of pancreas:-
Insulin:
Insulin is a peptide hormone and plays an important role in glucose homeostasis. It’s main effect is to lower blood glucose levels by increasing the uptake of glucose into the body cells, especially muscle and fat cells. Insulin also inhibits the breakdown of glycogen to glucose, the conversion of amino acids or fats to glucose, so insulin is rightly called a hypoglycemic hormone.

Glucagon:
Glucagon is a polypeptide hormone. It is a potent hyperglycaemic hormone that acts on the liver and promotes the breakdown of glycogen to glucose (Glycogenolysis), synthesis of glucose from lactic acid and from non-carbohydrate molecules (gluconeogenesis).

Releases glucose from the liver cells, increasing the blood glucose levels. Since glucagon reduces the cellular uptake and utilisation of glucose it is called a hyperglycemic hormone. Prolonged hyperglycemia leads to the disorder called diabetes mellitus.

Question 19.
Explain the endorenal function of gonads?
Answer:
Testis:
A pair of testis is present in the scrotal sac of males. The testis functions as a sex organ and also as an endocrine gland. The testis is composed of seminiferous tubules and interstitial cells or Leyding cells. The Leyding cells secrete several male sex hormones, collectively called androgens, mainly testosterone.

Functions of testosterone:
Under the influence of FSH and LH testosterone initiates maturation of male reproductive organs, and the appearance of secondary sexual characters, muscular growth, growth of facial and axillary hair, masculine voice and male sexual behaviour. It enhances the total bone matrix and plays a stimulating role in the process of spermatogenesis.

Ovary:
Females have a pair of ovaries located in the pelvic region of the abdomen. The ovary is composed of ovarian follicles and stromal tissues. Besides producing the eggs or ova, the ovaries secrete the steroid hormones oestrogen and progesterone. Oestrogen is responsible for the maturation of reproductive organs and the development of secondary sexual characters at puberty. Along with progesterone, oestrogens promotes breast development and initiate the cyclic changes during menstrual cycle.

Progesterone prepares the uterus for implantaion of the fertilized ovum. It decreases the uterine contraction during pregnancy and stimulates mammary glands and milk secretion. It is responsible for premenstrual changes in the uterus and is essential for the formation of placenta.

Question 20.
Write the disorders associated with growth hormone?
Answer:
Dwarfism is due to hyposecretion of growth hormone (GH) in children, skeletal growth and sexual maturity is arrested. They attain a maximum height of 4 feet only. Gigantism is due to hypersecreion of growth hormone (GH) in children. Overgrowth of skeletal structure occurs (up to 8 feet) and the visceral growth is not appropriate with that of limbs.

Acromegaly is due to excessive secretion of growth hormone in adults. Over growth of hand bones, feet bones, jaw bones, malfunctioning of gonads, enlargement of viscera, tongue, lungs, heart, liver, spleen and endocrine gland like thyroid, adrenal etc., are the symptoms of acromegaly.

Question 21.
Write on Hyperthyroidism and Hypothyroidism?
Answer:
In infants, hypothyroidiam causes cretinism. A cretins shows retarded skeletal growth, absence of sexual maturity, retarded mental ability, thick wrinkled skin, protruded enlarged tongue, bloated face, thick and short limbs occurs. The other symptoms are low BMR, slow pulse rate, subnormal body temperature and elevated blood cholesterol level.

Hyposecretion of thyroid in adults causes myxodema. It is otherwise called Gull’s disease. This disease is characterised by decreased mental activity, memory loss, slowness of movement, speech, and general weakness of body, dry coarse skin, scarce hair, puffy appearence, disturbed sexual function, low BMR, poor appetite, and subnormal body temperature.

Grave’s disease also called as thyrotoxicosis or exophthalmic goitre. This disease is caused due to hyper secretion of thyriod. It is characterised by enlargement of thyroid gland, increases BMR (50% -100%), elevated respiratory and excretory rates, increased heart beat, high BP, increases body temperature, protrusion of eyeball and weakness of eye muscles and weight loss.

Simple goitre is also known as Endemic goitre. It is caused due to hyposecretion of thyroxine. The symptoms includes enlargement of thyroid gland, fall in serum thyroxine level, increases TSH secretion.

Question 22.
Write on the disorders associated with parathryroid gland?
Answer:
Tetany is caused due to the hyposecretion of parathyroid hormone (PTH). Due to hyposecretion of PTH serum calcium level decreases (Hypocalcemia), as a result serum phosphate level increases. Calcium and phosphate excretion level decreses. Generalized convulsion, locking of jaws increased heart beat rate, increases body temperature, muscular spasm are the major symptoms of tetany. Hyperparathyroidism is caused due to excess PTH in blood. Demineralisation of bone, loss of muscle tone, general weakness, renal disorders are the symptoms of hyperparathyroidism.

Question 23.
Write a paragraph on Addison’s disease?
Answer:
Addison’s disease is caused due to hyposecretion of glucocorticoids and mineralocorticoids from the adrenal cortex. Muscular weakness, low BP, loss of appetite, vomiting, hyper pigmentation of skin, low metabolic rate, subnormal temperature, reduced blood volume – weight loss are the symptoms that occur in Addison’s disease. Reduces aldosterone secretion increases urinary excretion of Na Cl. and decreases potassium excretion leading to dehydration.

Question 24.
Write a paragraph on Cushing’s syndrome?
Answer:
Cushing’s syndrome is caused due to excess secretion of cortisol. Obesity of the face and trunk, redness of face, hand, feet, thin skin, excessive hair growth, loss of minerals from bone (osteoporoses) systolic hypertension are features of Cushing’s syndrome. Suppression of sexual function like atrophy of gonads are the other symptoms of Cushing’s syndrome.

Question 25.
Write on Hypoglycaemia?
Answer:
Hypoglycaemia is due to increased secretion of insulin thereby blood glucose level decreases. In this disorder blood glucose level lowers than normal fasting index. Increased heartbeat, weakness, nervousness, headache, confusion, lack of co-ordination, slurred speech, serious brain defects like epilepsy and coma occurs.

Question 26.
Write a paragraph on different types of diabetes mellitus?
Answer:
Hyperglycaemia is otherwise known as Diabetes mellitus. Is is caused due to reduced secretion of insulin. As the result, blood glucose level is elevated. Diabetes mellitus is of two types, Type! Diabetes and Type II Diabetes. Type I diabetes is also known Insulin dependent diabetes, caused by the lack of insulin secretion due to illness or viral infections. Type II diabetes is also known as Non-Insulin dependent diabetes, caused due to reduced sensitivity to insulin, often called as insulin resistance.

Symptoms of diabetes includes, polyurea (excessive urination), polyphagia (excessive intake of food), polydipsia (excessive consumption of liquids due to thirst), ketosis (breakdown of fat into glucose results in accumulation of ketone bodies) in blood. Gluconeogenesis (Conversion of non- carbohydrate) also occur in diabetes.

Question 27.
Explain the mechanism of hormone action?
Answer:
Peptide hormones cannot cross the phospolipid cell membrane and bind to the receptors on the exterior cell surface. They are transported to the golgi, which is the site of modification. It acts as a first messenger in the cell. Hormones on binding to their receptors do not enter target cell but generate the production of second messengers such as cyclic AMP (cAMP), which in turn regulates cellular metabolism.

This is catalyzed by the enzyme adenylate cyclase. The interaction between the hormone at the surface and the effect brought out by cAMP within the cell is known as signaling cascade. At each step there is a possibility of amplification.

1. One hormone molecule may bind to multiple receptor molecule before it is degraded.
2. Each receptor may activate several adenylate cyclases each of which make much CAMP.
3. Thus there is more signal after each step.

The actions of CAMP are terminated by phosphodiesterases. The effect of peptide hormones like insulin, glucagon, somatotropin are uauslly short lived because they work through second messenger system.

Steroid hormones can easily cross the cell membrane, and bind to their receptors, which are intracellular or intranuclear. Upon binding to the receptors, they pair up with another receptor – hormone complex (dimerize). This dimer can then bind to DNA and alter its transcription.

The effect of steroid hormones such as aldosterone, FSH are long lived, as they alter the amount of mRNA and protein in a cell.

Amino acid derived hormones are derived from one or two aminoacid with a few additonal modifications. Thyroid hormone is synthesised from thyrosine and includes the addtion of several iodine atoms. Epinephrine an amino acid derivative may function through second messenger system like peptide hormone or they may actually enter the cell and function like steroid hormones.

Question 28.
Tabulate the major hypothalamic hormones and their functions?
Answer:

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Samacheer Kalvi 11th Bio Zoology Neural Control and Coordination Text Book Back Questions and Answers

Textbook Evaluation Solved
Choose The Correct Answer
Question 1.
Which structure in the ear converts pressure waves to action potentials?
(a) Tympanic membrane
(b) Organ of Corti
(c) Oval window
(d) Semicircular canal
Answer:
(b) Organ of Corti

Question 2.
Which of the following pairings is correct?
(a) Sensory nerve – afferent
(b) Motor nerve – afferent
(c) Sensory nerve – ventral
(d) Motor nerve – dorsal
Answer:
(a) Sensory nerve – afferent

Question 3.
During synaptic transmission of nerve impulse, neurotransmitter (P) is released from synaptic vesicles by the action of ions (Q)? Choose the correct P and Q?
(a) P = Acetylcholine, Q = Ca^+–
(b) P = Acetylcholine, Q = Na⁺
(c) P = GABA, Q = Na⁺
(d) P = Cholinesterase, Q = Ca⁺⁺
Answer:
(a) P = Acetylcholine, Q = Ca^+–

Question 4.
Examine the diagram of the two cell types A and B given below and select the correct option?

(a) Cell-A is the rod cell found evenly all over retina
(b) Cell-A is the cone cell more concentrated in the fovea centralis
(c) Cell-B is concerned with colour vision in bright light
(d) Cell-A is sensitive to bright light intensities
Answer:
(c) Cell-B is concerned with colour vision in bright light

Question 5.
Assertion: The imbalance in concentration of Na⁺, K⁺ and proteins generates action potential.
Reason: To maintain the unequal distribution of Na⁺ and K⁺, the neurons use electrical energy.
(a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Answer:
(a) Both Assertion and Reason are true and Reason ¡s the correct explanation of the Assertion.

Question 6.
Which part of the human brain is concerned with the regulation of body temperature?
(a) Cerebellum
(b) Cerebrum
(c) Medulla oblongata
(d) Hypothalamus
Answer:
(a) Cerebellum

Question 7.
The respiratory centre is present in the …………………..
(a) Medulla oblongata
(b) Hypothalamus
(c) CerebeLlum
(d) Thalamus
Answer:
(a) Medulla oblongata

Question 8.
Match the following human spinal nerves in column-I with their respective number in column-II and choose the correct option?

(P – iv), (Q – iii), (R – i), (S – ii)
(b) (P – iii), (Q – i), ( R – ii), (S – iv)
(c) (P – iv), (Q – i), (R – ii), ( S – iii)
(d) (P – ii), (Q – iv), (R – i), (S – iii)
Answer:
(a) (P -iv)
(b) (Q – iii)
(c) (R – i)
(d) (S – ii)

Question 9.
Which of the following cranial nerve controls the movement of eye ball ?
(a) Trochlear nerve
(b) Optic nerve
(c) Olfactory nerve
(d) Vagus nerve
Answer:
(a) Trochlear nerve

Question 10.
The abundant intracellular cation is ………………….
(a) H⁺
(b) K⁺
(c) Na⁺
(d) Ca⁺⁺
Answer:
(b) K⁺

Question 11.
Which of the following statement is wrong regarding conduction of nerve impulse?
(a) In a resting neuron, the axonal membrane is more permeable to K⁺ ions and nearly impermeable to Na⁺ ions.
(b) Fluid outside the axon has a high concentration of Na⁺ ions and low concentration of K⁺, in a resting neuron.
(c) Ionic gradients are maintained by Na-K pumps across the resting membrane, which transport 3Na⁺ ions outwards for 2K⁺ into the cell.
(d) A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.
Answer:
(d) A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.

Question 12.
All of the following are associated with the myelin sheath except ………………….
(a) Faster conduction of nerve impulses
(b) Nodes of Ranvier forming gaps along the axon
(c) Increased energy output for nerve impulse conduction
(d) Saltatory conduction of action potential
Answer:
(c) Increased energy output for nerve impulse conduction

Question 13.
Several statements are given here in reference to cone cells. Which of the following option indicates all correct statements for cone cells?
Statements:
(i) Cone cells are less sensitive in bright light than Rod cells
(ii) They are responsible for colour vision
(iii) Erythropsin is a photo pigment which is sensitive to red colour light
(iv) They are present in fovea of retina
(a) (iii), (ii) and (i)
(b) (ii), (iii) and (iv)
(c) (i), (iii) and (iv)
(d) (i), (ii) and (iv)
Answer:
(b) (ii), (iii) and (iv)

Question 14.
Which of the following statement concerning the somatic division of the peripheral neural system is incorrect?
(a) Its pathways innervate skeletal muscles
(b) Its pathways are usually voluntary
(c) Some of its pathways are referred to as reflex arcs
(d) Its pathways always involve four neurons
Answer:
(d) Its pathways always involve four neurons

Question 15.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of …………………
(a) Depolarization
(b) Hyperpolarization
(c) Repolarization
(d) Hypopolarization
Answer:
(b) Hyperpolarization

Question 16.
Why is the blind spot called so?
Answer:
Slightly below the posterior pole of the eye, the optic nerve and the retinal blood vessels enter the eye. This region is devoid of rods and cones. Hence, this region is called blind spot.

Question 17.
Sam’s optometrist tells him that his intraocular pressure is high. What is this condition called and which fluid does it involve?
Answer:
The aqueous humour present in between iris and lens and the cornea and iris is produced and drained at the same rate, maintaining a constant intra ocular pressure of about 16 mm Hg. Any block in the canal of schlemm increases the intra ocular pressure of aqueous humour. This condition is called ‘Glaucoma’. Due to pressure, optic nerve and the retina are compressed. This leads to blindness.

Question 18.
Why are we getting running nose while crying?
Answer:
When we cry, the tears come out of the tear glands under the eyelids and drain through the tear duct that empty into the nose. It mixes with mucus there and the nose runs.

Question 19.
The action potential occurs in response to a threshold stimulus; but not at subthreshold stimuli. What is the name of the principle involved?
Answer:
All or none principle.

Question 20.
Pleasant smell of food urges Ravi to rush into the kitchen. Name the parts of the brain involved in the identification of food and emotional responses to odour?
Answer:
Olfactory nerve carries the sense of smell to the sensory strip present in the cerebrum. The sensory areas are present in the parietal lobe of the cerebrum. The stimuli of smell reaches the mammillary bodies present in the hypothalamus. This produces olfactory reflexes and emotional responses to odour.

Question 21.
Cornea transplant in humans is almost never rejected. State the reason?
Answer:
Cornea does not have blood vessels. Hence there is no possibility of rejection when cornea is transplanted from one person to another person.

Question 22.
At the end of repolarization, the nerve membrane gets hyperpolarized. Why?
Answer:
At the end of repolarization, the membrane potential inside the axolemma becomes negative due to the efflux of K⁺ ions. When it becomes more negative than the resting potential -70 mV to about – 90mV, it becomes hyperpolarised.