Category: Class 8

Students can Download Maths Chapter 1 Numbers Intext Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 3 Chapter 1 Numbers Intext Questions

Exercise 1.1
Think (Text book page No. 3)

Question 1.
Is the square of a prime number, prime?
Solution:
No, the square of a prime number ‘P’ has at least 3 divisors 1, P and P². But a prime number is a number which has only two divisors, 1 and the number itself. So square of a prime number is not prime.

Question 2.
Solution:
The sum of two perfect squares, need not be always a perfect square. Also the difference of two perfect squares need not be always a perfect square. Bu the product of two perfect square is a perfect square.

Try These (Text book Page No. 3)

Consider the following square numbers:
(i) 441
(ii) 225
(iii) 289
(iv) 1089.
Express each of them as the sum of two consecutive positive integers.
Solution:
(i) 441 = 220 + 221
(ii) 225 = 112 + 113
(iii) 289 = 144 + 145
(iv) 1089 = 544 + 545

Think (Text book Page No. 4)

Question 1.
Take an even natural number, say, 46 (or any other even number of your choice). Try to express it as a sum of consecutive odd numbers starting with 1. Do you succeed?
Solution:
1 + 3 + 5 + 7 + 9 + 11 = 36
1 + 3 + 5 + 7 + 9 + 11 + 13 = 49
So 46 cannot be expressed as a sum of consecutive odd numbers starting with 1. But 36 also an even natural number. It can be expressed as the sum of consecutive odd numbers as 36 = 1 +3 + 5 + 7 + 9 + 11.

Question 2.
The square of an odd number can always be written as the sum of two consecutive natural numbers. Can the reverse statement be true? Is the sum of any two consecutive natural numbers a perfect square of a number?
Solution:
No, the reverse is not true. The sum of any two consecutive natural numbers need not be a perfect square of a number. Example: 35 + 36 = 71, not a perfect square.

Try These (Text book Page No. 4)

(i) Which among 256, 576, 960, 1025, 4096 are perfect square numbers?
(Hint: Try to extend the table of squares already seen).
Solution:
256 = 16²
576 = 24²
4096 = 64²
∴ 256, 576 and 4096 are perfect squares

(ii) One can judge just by look, that the each of the following numbers (82, 113, 2057, 24353, 8888,1972) is not a perfect square. Explain why?
Solution:
Because the unit digit of a perfect square will be 0, 1, 4, 5, 6, 9. But the given numbers have unit digits 2, 3, 7, 8. So they are not perfect squares.

(iii) Find the squares by diagonal method and also the ones digit in the squares of the following numbers: 11, 27, 42, 79, 146, 324, 520.
Solution:
Ones digit is the squares of

Think (Text book Page No. 5)

Consider the claim: “Between the squares of the consecutive numbers n and (n+1), there are 2n non-square numbers”. Can it be true? Find how many non-square numbers are there
(i) between 4 and 9?
(ii) between 49 and 64?
and verify the claim.
Solution:

Therefore we conclude that there are 2n non-square numbers between two consecutive square numbers.

Activity 1. (Text book Page No. 5)

Verify the following statements:
(i) The square of a natural number, other than 1, is either a multiple of 3 or exceeds a multiple of 3 by 1.
Verification

Hence verified that the square of a natural number other than 1, is either a multiple of 3 or exceeds a multiple of 3 by 1.

(ii) The square of a natural number, other than 1, is either a multiple of 4 or exceeds a multiple of 4 by 1.
Verification

So a perfect square leaves remainder 0 or 1 on division by 4.

(iii) The remainder of a perfect square when divided by 3, is either 0 or 1 but never 2.
Verification

So in all the cases the remainder is either 0 or 1, but not 2. Hence verified.

(iv) The remainder of a perfect square, when divided by 4, is either 0 or 1 but never 2 and 3.
Verification

From the table it is verified that the remainder of a perfect square when divided by 4 is either 0 or 1 but never 2 and 3.

(v) When a perfect square number is divided by 8, the remainder is either 0 or 1 or 4, but never be equal to 2, 3, 5, 6 or 7.
Verification

From the table it is verified when a perfect square number is divided by 8, the remainder is 0 or 1 or 4. but never be equal to 2, 3, 5, 6 or 7

Activity 2. (Text book Page No. 6)

Consider any natural number m > 1.We find that (2m, m² – 1, m² + 1) will form a Pythagorean triplet. (A little algebra can help you to verify this!). With this formula, generate a few Pythagorean triplets.
Solution:
For any natural number m, we have 2m, m² – 1, m² + 1 is a Pythagorean triplet.
(i) Consider 2m = 16 ⇒ m = 8
m² – 1 = 64 – 1 = 63
m² + 1 = 64 + 1 = 65
So Pythagorean triplet is 16, 63, 65.

(ii) Consider 2m = 18 ⇒ m = 9
m² – 1 = 81 – 1 = 80
m² + 1 = 81 + 1 = 82
So Pythagorean triplet is 18, 80, 82.

Try These (Text book Page No. 7)

Use the method of successive subtraction of odd numbers (starting from 1) to examine the following numbers and find if they are perfect squares or not. For perfect square numbers that you find, identify the square root.
(i) 144
(ii) 256
(iii) 360
Solution:
(i) 144
Step 1: 144 – 1 = 143
Step 2: 143 – 3 = 140
Step 3: 140 – 5 = 135
Step 4: 135 – 7 = 128
Step 5: 128 – 9 = 119
Step 6: 119 – 11 = 108
Step 7: 108 – 13 = 95
Step 8: 95 – 15 = 80
Step 9: 80 – 17 = 63
Step 10: 63 – 19 = 44
Step 11: 44 – 21 = 23
Step 12: 23 – 23 = 0.
We get 0 in the 12th step. ∴ 144 is a perfect square and ∴ \(\sqrt{144} \) = 12.

(ii) 256
Step 1: 256 – 1 = 255
Step 2: 255 – 3 = 252
Step 3: 252 – 5 = 247
Step 4: 247 – 7 = 240
Step 5: 240 – 9 = 231
Step 6: 231 – 11 = 220
Step 7: 220 – 13 = 207
Step 8: 207 – 15 = 192
Step 9: 192 – 17 = 175
Step 10: 175 – 19 = 156
Step 11: 156 – 21 = 135
Step 12: 135 – 23 = 112
Step 13: 112 – 25 = 87
Step 14: 87 – 27 = 60
Step 15: 60 – 29 = 31
Step 16: 31 – 31 = 0
We have subtracted odd numbers starting from 1 repeatedly from 256. We get 0 in the 1 step.
∴ 256 is a perfect square and \(\sqrt{256} \) = 16.

(iii) 360
Step 1: 360 – 1 = 359
Step 2: 359 – 3 = 356
Step 3: 356 – 5 = 351
Step 4: 351 – 7 = 344
Step 5: 344 – 9 = 335
Step 6: 335 – 11 = 324
Step 7: 324 – 13 = 311
Step 8: 311 – 15 = 296
Step 9: 296 – 17 = 279
Step 10: 279 – 19 = 260
Step 11: 260 – 21 = 239
Step 12: 239 – 23 = 216
Step 13: 216 – 25 = 191
Step 14: 191 – 27 = 164
Step 15: 164 – 29 = 135
Step 16: 135 – 31 = 104
Step 17: 104 – 33 = 71
Step 18: 71 – 35 = 36
Step 19: 36 – 37 = -1
We have subtracted successive odd numbers starting from 1, repeatedly from 360, we didn’t get zero.
∴ The given number is not perfect square.

Think (Text book Page No. 8)

In this case, if we want to find the smallest factor with which we can multiply or divide 108 to get a square number, what should we do?
Solution:
108 = 2 × 2 × 3 × 3 × 3 = 2² × 3² × 3
If we multiply the factors by 3, then we get
2² × 3² × 3 × 3 ⇒ 2² × 3² × 3² = (2 × 3 × 3)²
Which is a perfect square.
∴ Again if we divide by 3 then we get 2² × 3² ⇒ (2 × 3 )², a perfect square.
∴ We have to multiply or divide 108 by 3 to get a perfect square.

Exercise 1.2
Try These (Text book Page No. 11)

Find the square root by long division method.
(i) 400
(ii) 1764
(iii) 4356
Solution:

Try These (Text book Page No. 12)

Question 1.
Without calculating the square root, guess the number of digits in the square root of the following numbers:
(i) 14400
(ii) 100000000
(iii) 390625
Solution:
(i) \(\sqrt{14400}=\sqrt{144 \times 100}=\sqrt{144} \times \sqrt{100}\) = 12 x 10 = 120.
(ii) \(\sqrt{100000000}=\sqrt{10000 \times 10000}=\sqrt{10000} \times \sqrt{10000}\) = 100 × 100 = 10,000
(iii) \(\sqrt{390625}=\sqrt{25 \times 25 \times 25 \times 25}=\sqrt{25 \times 25} \times \sqrt{25 \times 25}\) = 25 x 25 = 625

Question 2.
Find the square root of
(i) 19.36
(ii) 1.2321
(iii) 116.64
Solution:

Think (Text book Page No. 13)

Fill up the table:

Solution:

Activity 3. (Text book Page No. 13)

Attempt to prepare a table of square root problems as in the above case to show that if a and b are two perfect square numbers, then \(\sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}\) (b ≠ 0) We can use this idea to compute easily certain square-root problems.
Solution:

Try These (Text book Page No. 13)

Using the above method, find the square root of 1.2321 and 11.9025.
Solution:
(i) \(\sqrt{1.2321}=\sqrt{\frac{12321}{10000}}=\frac{111}{100}\) = 1.11
(ii) \(\sqrt{11.9025}=\frac{\sqrt{119025}}{\sqrt{10000}}=\frac{345}{100}\) = 3.45

Try These (Text book Page No. 14)

Put the numbers
(i) 4, \(\sqrt{14} \), 5 and
(ii) 7, \(\sqrt{65} \), 8 in ascending order.
Solution:
(i) 4, \(\sqrt{14} \), 5
Squaring all the numbers we get 4², \((\sqrt{14})^2 \) , 5² ⇒ 16, 14, 25
∴Ascending order: 14, 16, 25
Ascending order: \(\sqrt{14} \), 4, 5

(ii) 7, \(\sqrt{65} \), 8
Squaring 7, \(\sqrt{65} \) and 8 we get 7², \((\sqrt{65})^2 \), 8² ⇒ 49, 65, 64
Ascending order: 49, 64, 65
Ascending order: 7, 8, \(\sqrt{65} \)

Exercise 1.3
Try These (Text book Page No. 17)

Find the ones digit in the cubes of each of the following numbers,
(i) 17
(ii) 12
(iii) 38
(iv) 53
(v) 71
(vi) 84
Solution:
(i) 17
17 ends with 7, so its cube ends with 3. i.e, ones digit in 17³ is 3.
(ii) 12
12 ends with 2, so its cube ends with 8. i.e, ones digit in 12³ is 8.
(iii) 38
38 ends with 8, so its cube ends with 2. i.e, ones digit in 38³ is 2.
(iv) 53
53 ends with 3, so its cube ends with 7. i.e, ones digit in 53³ is 7.
(v) 71
71 ends with 1, so its cube ends with 1. i.e, ones digit in 71³ is 1
(vi) 84
84 ends with 4, so its cube ends with 4. i.e, ones digit in 84³ is 4.

Think (Text book Page No. 17)

Find the smallest number by which 675 must be divided to obtain a perfect cube.
Solution:

We find that 675 = 3 x 3 x 3 x 5 x 5
= 3 x 3 x 3 x 5 x 5
Here we have an ungrouped 5 x 5.
So if we divide 675 by 5 x 5 then the new number will be a perfect cube.
ie. 675 ÷ 25 = 27
The new number is 27
\(\sqrt[3]{27}=\sqrt[3]{3 \times 3 \times 3}\) = 3

Exercise 1.4
Try These (Text book Page No. 21)

Expand the following numbers using exponents:
(i) 8120
(ii) 20305
(iii) 3652.01
(iv) 9426.521
Solution:
(i) 8120 = (8 x 1000) + (1 x 100) + (2 x 10) + 0 x 1
= (8 x 10³) + (1 x 10²) + (2 x 10¹)

(ii) 20305 = (2 x 10000) + (0 x 1000) + (3 x 100) + (0 x 10) + (5 x 1)
= (2 x 10⁴) + (3 x 10²) + 5

(iii) 3652.01 = 3000 + 600 + 50 + 2 + \(\frac{0}{10}+\frac{1}{100}\)
= (3 x 1000) +(6 x 100) + (5 x 10) + (2 x 1) + (1 x \(\frac{1}{100}\))
= (3 x 10³) + (6 x 10²) + (5 x 10¹) + 2 + (1 x 10^-2)

(iv) 9426.521 = (9 x 1000) + (4 x 100) + (2 x 10) + (6 x 1) + \(\left(\frac{5}{10}\right)+\left(\frac{2}{100}\right)+\left(\frac{1}{1000}\right)\)
= (9 x 10³) + (4 x 10²) + (2 x 10¹) + 6 + (5 x 10^-1) + (2 x 10^-2) + (1 x 10^-3)

Try These (Text book Page No. 23)

Verify the following laws (as we did above). Here, a, b are non-zero integers and m, n are any integers.
1. Zero exponent rule: a⁰ = 1.
2. Product of same powers to power of product rule: a^m x b^m = (ab)^m
3. Quotient of same powers to power of quotient rule: \(\frac{a^{m}}{b^{m}}=\left(\frac{a}{b}\right)^{m}\)
Verification:
Let a = 2; b = 3; m = 2
1. a⁰ = 2⁰ = 1.
2. a^m x b^m = 2² x 3² = 4 x 9 = 36 = (2 x 3)²
3. \(\frac{a^{m}}{b^{m}}=\frac{2^{2}}{3^{2}}=\frac{4}{9}=\left(\frac{2}{3}\right)^{2}\)

Try These (Text book Page No. 26)

Question 1.
Write in standard form: Mass of planet Uranus = 8.68 x 10²⁵ kg.
Solution:
Mass of Planet Uranus = 86800000000000000000000000 kg
[23 zeros after 868]

Question 2.
Write in scientific form:
(i) 0.000012005
(ii) 4312.345
(iii) 0.10524
(iv) The distance between the Sun and the planet Saturn 1.4335 x 10¹² miles.
Solution:

(iv) The distance between Sun and the planet Saturn is 1.4335 x 10¹² miles

Activity 4. (Text book Page No. 29)

Observe that
2³ – 1³ = 1 + 2 x 1 x 3
3³ – 2³ = 1 + 3 x 2 x 3
4³ – 3³ = 1 + 4 x 3 x 3
Find the value of 15³ – 14³ in the above pattern.
Solution:
15³ – 14³ = 1 + 15 x 14 x 3

Think (Text book Page No. 29)

1³ = 1 = 1
2³ = 8 = 3 + 5
3³ = 27 = 7 + 9 + 11
Observe and continue this pattern to find the value of 73 as the sum of consecutive odd numbers.
1³ = 1 = 1
2³ = 8 = 3 + 5
3³ = 27 = 7 + 9 + 11
4³ = 64 = 13 + 15 + 17 + 19
5³ = 125 = 21 + 23 + 25 + 27 + 29
6³ = 216 = 31 + 33 + 35 + 37 + 39 + 41
7³ = 343 = 43 + 45 + 47 + 49 + 51 + 53 + 55

Students can Download Science Term 3 Chapter 6 Chemistry in Everyday Life Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Science Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Science Solutions Term 3 Chapter 6 Chemistry in Everyday Life

Samacheer Kalvi 8th Science Chemistry in Everyday Life Text Book Exercise

I. Choose the best answer:

Question 1.
The chemical mixed with LPG that helps in the detection of its leakage is …………………
(a) methanol
(b) ethanol
(c) camphor
(d) mercapton
Answer:
(d) mercapton

Question 2.
Which is known as syn gas?
(a) Marsh gas
(b) Water gas
(c) Producer gas
(d) Coal gas
Answer:
(b) Water gas

Question 3.
The unit of calorific value of fuel is …………………
(a) kilo joule per mole
(b) kilo joule per gram
(c) kilo joule per kilo gram
(d) joule per kilo gram
Answer:
(c) kilo joule per kilo gram

Question 4.
………………… is the coal of superior quality.
(a) Peat
(b) Lignite
(c) Bituminous
(d) Anthracite
Answer:
(d) Anthracite

Question 5.
The main component of natural gas is …………………
(a) methane
(b) ethane
(c) propane
(d) butane
Answer:
(a) methane

II. Fill in the blanks:

1. Producer gas is a mixture of …………..
2. ………….. is known as marsh gas.
3. The term petroleum means …………..
4. Heating coal in the absence of air is called ……………
5. An example for fossil fuel is …………..

Answer:

1. Carbon monoxide and nitrogen
2. Methane
3. Rock oil
4. Destructive distillation
5. Coal

III. Match the following:

Question 1.

1. Octane rating – (a) Diesel
2. Cetane rating – (b) Methane
3. Simplest hydrocarbon – (c) Petrol
4. Peat – (d) Bown in colour
5. Lignite – (e) First stage coal

Answer:

1. c
2. a
3. b
4. e
5. d

IV. Answer briefly:

Question 1.
What do you mean by catenation?
Answer:
The property of carbon atom to form bonds with itself resulting in a single large structure or chain is called catenation.

Question 2.
Mention the advantages of natural gas.
Answer:

1. It produces lot of heat as it is easily burnt.
2. It does not leave any residue.
3. It bums without smoke and so causes no pollution.
4. This can be easily supplied through pipes.
5. It can be directly used as fuel in homes and industries.

Question 3.
Expand CNG. List out its uses.
Answer:
CNG – Compressed Natural Gas.

1. It is the cheapest and cleanest fuel.
2. Vehicles using this gas produce less carbon dioxide and hydrocarbon emission.
3. It is less expensive than petrol and diesel.

Question 4.
Identify the gas known as syngas. Why is it called so?
Answer:
Water Gas is also called as syngas or synthesis gas as it is used to synthesize methanol and simple hydrocarbons. It is used as an industrial fuel also.

Question 5.
Anthracite is known as the highest grade coal. Give reason.
Answer:

1. Anthracite is the highest grade coal.
2. It has a very light weight and the highest heat content.
3. Anthracite coal is very hard, deep black and shiny.
4. It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
5. It bums longer with more heat and less dust.

Question 6.
Distinguish between octane number and cetane number.
Answer:
Octane Number:

1. Octane rating is used for petrol
2. It measures the amount of octane present in petrol
3. Octane number of petrol can be increased by adding benzene or toluene.
4. The fuel with high octane number has low cetane number

Cetane Number:

1. Cetane rating is used for diesel
2. It measures the ignition delay of the fuel in diesel engine.
3. Cetane number of diesel can be increased by adding acetone.
4. The fuel with high cetane number has low octane number

Question 7.
Name the places in Tamilnadu harnessing wind energy from wind mills.
Answer:
Wind mills are mostly located at Kayathar, Aralvaimozhi, Palladam and Kudimangalam in Tamil Nadu.

Question 8.
Solar energy is a non – depleting energy. Justify.
Answer:

1. Solar energy is the only viable fuel source of non – depleting nature for, Sun provides a free and renewable source of energy.
2. It is the renewable type of energy without endangering the environment.
3. It is the potential source to replace the fossil fuel in order to meet the needs of the world. With the advancements in science and technology, solar energy has become more affordable, and it can overcome energy crisis.

V. Answer in detail:

Question 1.
Explain the different types of coal.
Answer:
Lignite:

1. Lignite is a brown coloured coal of lowest grade.
2. It has least content of carbon. The carbon content of lignite is 25 – 35%.
3. Lignite contains a high amount of water and makes up almost half of our total coal reserves.
4. It is used for electricity generation.
5. It is used to generate synthetic natural gas and produce fertilizer products.

Sub-bituminous:

1. When lignite becomes darker and harder over time, sub-bituminous coal is formed.
2. Sub-bituminous coal is a black and dull coal.
3. It has higher heating value than lignite and contains 35-44% carbon.
4. It is used primarily as fuel for electricity power generation.
5. This coal has lower sulfur content than other types and bums cleaner.

Bituminous:

1. With more chemical and physical changes, sub-bituminous coal is developed into bituminous coal.
2. It is dark and hard. It contains 45-86% carbon. It has high heating value.
3. It is used to generate electricity.
4. Other important use of this coal is to provide coke to iron and steel industries.
5. By-products of this coal can be converted into different chemicals which are used to make paint, nylon and many other items.

Anthracite:

1. It is the highest grade coal. It is hard and dark black in colour.
2. It has a very light weight and the highest heat content.
3. Anthracite coal is very hard, deep black and shiny.
4. It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
5. It bums longer with more heat and less dust.

Question 2.
What is known as destructive distillation? Write about the products obtained from petroleum.
Answer:
Coal when heated in the absence of air does not bum but produces many by-products. This process of heating coal in the absence of air is called destructive distillation of coal.
Products obtained from petroleum:

1. Liquefied Petroleum Gas or LPG
2. Diesel and petrol
3. Kerosene
4. Lubricating oil
5. Paraffin
6. Bitumen or asphalt
7. Refinery Gas
8. Naphtha
9. Fuel Oil
10. Chemicals
11. Jet fuel
12. Waxes
13. Polishes

Question 3.
What are the different types of fuels?
Answer:
Fuels are classified into solid, liquid and gaseous fuels according to their physical state.
Solid fuels:

1. Fuels like wood and coal are in solid state and they are called solid fuels.
2. This type of fuel was the first one to be used by man.
3. These fuels are easy to store and transport.
4. The production cost is also very low.

Liquid fuels:

1. Most of the liquid fuels are derived from the fossil remains of dead plants and animals petroleum oil, coal tar and alcohol are some of the liquid fuels.
2. These fuels give more energy on burning and bum without ash.

Gaseous fuel:

1. Coal gas, oil gas, producer gas and hydrogen are some of the gaseous fuels.
2. It can be easily transported through pipes and they do not produce pollution.

Samacheer Kalvi 8th Science Chemistry in Everyday Life Additional Questions

I. Choose the correct answer:

Question 1.
Dead and decaying plants and animals release ………………… gas.
(a) propane
(b) butane
(c) methane
(d) pentane
Answer:
(c) methane

Question 2.
………………… is an odourless and highly inflammable gas.
(a) Propane
(b) Butane
(c) Ethane
(d) Methane
Answer:
(a) Propane

Question 3.
Which gas is used as fuels and solvents in the laboratory?
(a) Natural gas
(b) CNG
(c) Methane
(d) Butane
Answer:
(d) Butanel

Question 4.
Which of the following is referred as wood gas?
(a) Water gas
(b) Producer gas
(c) Coal gas
(d) None
Answer:
(b) Producer gas

Question 5.
Which is used in museums to protect the monuments?
(a) CNG
(b) Producer Gas
(c) Water gas
(d) Natural gas
Answer:
(d) Natural gas

Question 6.
………………… is a mixture of methane and carbon dioxide.
(a) Bio-gas
(b) Water gas
(c) Coal gas
(d) None
Answer:
(a) Bio-gas

Question 7.
………………… is a gaseous mixture of carbon monoxide and hydrogen.
(a) Bio-gas
(b) Natural gas
(c) Water gas
(d) Producer gas
Answer:
(b) Natural gas

Question 8.
The breaking down of organic matter in an anaerobic condition leads to the formation of ………………….
(a) coal gas
(b) natural gas
(c) bio-gas
(d) CNG
Answer:
(c) Bio-gas

Question 9.
When lignite becomes darker and harder over time ………………… coal is formed.
(a) lignite
(b) bituminous
(c) anthracite
(d) sub-bituminous
Answer:
(d) sub-bituminous

Question 10.
Which one among the following is an extremely strong but lightweight material is used in mountain bikes and tennis rackets?
(a) Cotton fibre
(b) Carbon fibre
(c) Plastic fibre
(d) None
Answer:
(b) Carbon fibre

II. Fill in the blanks:

1. Hydrogen gas obtained from natural gas is used in the production of …………….
2. Hydrocarbons are present in different ……………. and …………….
3. Hydrocarbons are less dense than …………….
4. Sewage sludge can also be decomposed by microorganisms to produce methane gas along with impurities like carbon dioxide and ……………..
5. ……………. can also be used as refrigerants.
6. ……………. is used as a fuel gas and propellant in aerosol sprays such as deodorants.
7. ……………. natural gas can be extracted through drilling wells.
8. ……………. coal is a black and dull coal.
9. ……………. is used to make face packs and cosmetics.
10. Activated carbon used in filters for water and air purification and in ……………. machines is obtained from coal.

Answer:

1. fertilizers
2. trees, plants
3. water
4. hydrogen sulphide
5. Propane
6. Butane
7. Conventional
8. Sub-bituminous
9. Activated charcoal
10. kidney dialysis

III. Write true or false- if false, write the correct statement:

Question 1.
Coal helps to create alumina refineries.
Answer:
True

Question 2.
Coke is used in the preparation of dyes, explosives, paints synthetic fibers and pesticides.
Answer:
False
Correct statement:
Coal tar is used in the preparation of dyes, explosives, paints, synthetic fibers and pesticides.

Question 3.
Coal is also known as black diamond owing to its precious nature.
Answer:
True

Question 4.
Crude oil is used as a sealant for waterproofing various surfaces.
Answer:
True

Question 5.
The process of separating petroleum into useful by-products and removal of undesirable impurities is called distillation.
Answer:
False
Correct statement:
The process of separating petroleum into useful by-products and removal of undesirable impurities is called refining.

IV. Match the following:

Question 1.

1. Hydrocarbons – (a) Marsh gas
2. Methane – (b) Cleanest fuel
3. Butane – (c) Catenation
4. CNG – (d) Polystryrene

Answer:

1. c
2. a
3. d
4. b

V. Short answer questions:

Question 1.
Write any 2 properties of hydrocarbons.
Answer:

1. Most of the hydrocarbons are insoluble in water.
2. Hydrocarbons are less dense than water. So they float on top of water.
3. Most hydrocarbons react with oxygen to produce carbon dioxide and water.

Question 2.
Write the uses of natural gas.
Answer:

1. Natural gas is used as an industrial and domestic fuel.
2. It is used in thermal power stations.
3. It is used as fuel in vehicles as an alternative for petrol and diesel.

Question 3.
Write a note on bio-gas.
Answer:

1. Bio-gas is a mixture of methane and carbon dioxide.
2. It is produced by the decomposition of plant and animal waste which form the organic matter.
3. The breaking down of organic matter in anaerobic condition (ie., in the absence of oxygen) leads to the formation of biogas.
4. It is an example for renewable source of energy.

Question 4.
What is surface mining?
Answer:
If the coal beds lie within 22 feet of the Earth’s surface, the top soil is removed and coal is dug out. This is called surface mining.

Question 5.
What is deep mining?
Answer:
In some places, coal beds are found very deep inside the Earth. In that case, underground tunnels are made to get this coal. This is called underground mining or deep mining.

Question 6.
Write a note on coke.
Answer:

1. Coke contains 98% carbon. It is porous, black and the purest form of coal.
2. It is a good fuel and burns without smoke.
3. It is largely used as a reducing agent in the extraction of metals from their ores.
4. It is also used in making fuel gases like producer gas and water gas which is a mixture of carbon monoxide and hydrogen.

Question 7.
What are the characteristics of fuel?
Answer:

1. It should be readily available.
2. It should be easily transportable
3. It should be less expensive
4. It should have high calorific value
5. It should produce large amount of heat
6. It should not leave behind any undesirable substances.

Question 8.
Write a note on bio – diesel.
Answer:
Bio diesel is a fuel obtained from vegetable oils such as soya bean oil, jatropha oil, corn oil, sunflower oil, cotton seed oil, rice-bran oil and rubber seed oil.

VI. Long Answer type Questions:

Question 1.
What are the uses of coal?
Answer:

1. Coal is used to generate heat and electricity.
2. It is used to make derivatives of silicon which are used to make lubricants, water repellents, resins, cosmetics, hair shampoos and toothpaste.
3. Activated charcoal is used to make facepacks and cosmetics.
4. It is used to make paper.
5. It helps to create alumina refineries.
6. Carbon fibre is an extremely strong but lightweight material is used in construction, mountain bikes, and tennis rackets.
7. Activated carbon used in filters for water and air purification and in kidney dialysis machines is obtained from coal.

Question 2.
Explain destructive distillation of Coal.
Answer:

1. The destructive distillation of coal can be carried out in the laboratories.
2. Finely powdered coal is taken in a test tube and heated.
   • At a particular temperature, coal breaks down to produce coke, coal tar, ammonia and coal gas.
   • Coal tar is deposited at the bottom of the second test tube and coal gas escapes out through the side tube.
   • Ammonia produced is absorbed in the water, forming ammonium hydroxide.
   • Finally, a black residue called coke is left in the first tube.

Students can Download English Poem 2 Lesson in Life Questions and Answers, Summary, Activity, Notes, Samacheer Kalvi 8th English Book Solutions Guide Pdf  helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th English Solutions Term 1 Poem Chapter 2 Lesson in Life

A. Comprehension Questions.

Question 1.
What is planting a flower is compared to?
Answer:
Planting a flower is compared to the blossoming of a friendship.

Question 2.
What does the tiniest creature need?
Answer:
Even the tiniest creature needs space in the world.

Question 3.
What do the smallest gifts deserve?
Answer:
Even the smallest gifts deserve a warm thank you.

Question 4.
What will happen if you fail to give importance to others?
Answer:
If we fail to give importance to others, they will feel sad.

Question 5.
What do you learn from your lessons in life?
Answer:
I express my friendship with others by respecting them.

Question 6.
Pick and write the rhyming words from the third stanza.
Answer:
‘sad’ and ‘bad’ are the rhyming words.

Question 7.
“Having a friend is like planting a flower”
What is the figure of speech used in this line?
Answer:
The figure of speech used in this line is “simile”.

Figures of speech.

a. Simile: Answer the following:

Question 1.
Write a sentence using ‘as fast as the wind’.
Answer:
He runs as fast as the wind.

Question 2.
Write a simile using the word ‘like’.
Answer:
They fought like cats and dogs.

Question 3.
Create a simile using the word ‘as’.
Answer:
As sweet as honey.

Question 4.
What does ‘smart as a fox’ mean?
Answer:
It means to be clever or cunning as a fox.

b. Metaphor:

Question 1.
Which of the given options is a Metaphor?
(a) Life is like a chocolate box.
(b) Raj is like his twin brother
(c) His words are pearls of wisdom
(d) The bus is slow as a snail.
Answer:
(c) His words are pearls of wisdom.

Question 2.
What does ‘The world is a stage” mean?
Answer:
The world is like a stage where all of us are merely actors.

Question 3.
Identify the Metaphor in the sentence:
Answer:
Her hair is always a rat’s nest in the morning, a Hair is always a rat’s nest.

Question 4.
Write a sentence on your own that includes a Metaphor.
Answer:
He was a lion in the battle.

Lesson in Life Additional Questions

I. Poem Comprehension.

Question 1.
Let’s be aware as we walk on this planet
Even the tiniest creature needs room.
(a) What should we aware of ?
Answer:
We should be aware that even the tiniest creature needs room.
(b) What do you mean by the term ‘as we walk on this planet’?
Answer:
It means that as long ‘as we live in this world’.

Question 2.
Lessons in life aren’t always so simple Nothing you’re given will ever come free
(a) Are ‘lessons in life’ simple?
Answer:
No, lessons in life are not so simple.
(b) What does the second line mean?
Answer:
It means that you are not going to get anything free of cost.

Question 3.
Even the smallest of gifts deserves “thank you”.
What should you say, even when receive a small gift?
Answer:
We should say ‘thank you’.

Question 4.
Know that you matter and you make a difference
(a) What does the above line tell us?
Answer:
The above line tells us that every human being is unique and important

II. Poetic Devices.

Question 1.
Having a friend is like planting a flower
(a) What is the poetic device used here?
Answer:
Simile is used here.

Question 2.
Lessons in life aren’t always so simple
(a) Pick out the alliterated words.
Answer:
Lessons – life; so – simple are the alliterated words.

Question 3.
Having a friend is like planting a flower
Show love and kindness it one day will bloom
Let’s be aware as we walk on this planet
Even the tiniest creature needs room.
(a) Mention the rhyme scheme in this stanza.
Answer:
‘abcb’ is the rhyme scheme in this stanza.

III. Short Questions and Answers.

Question 1.
How can having a friend be like planting a flower?
Answer:
Both friendship and planting flowers will bloom one day, when we show love, kindness and care every day.

Question 2.
When do we feel sad?
Answer:
We feel sad when people don’t remember us.

Question 3.
How does the poet explain that everyone is important?
Answer:
The poet says that everyone is important and each makes a difference. Since we are important we must not allow others to shame us or make us feel bad.

Question 4.
Why do you think the second stanza has been repeated as the 4 stanza?
Answer:
The message that we learn a lot of lessons in life after going through difficulty and that if anyone gives us even a very small present, it is not without effort, the importance of gratitude in life and respect for people, have been repeated.

Question 5.
To whom does T and’You’refer to?
Answer:
I refers to the poet and you refers to the reader.

IV. Paragraph Questions with Answers.

Question 1.
How should we treat a flowering plant and true friendship?
Answer:
The poet compares planting flowers to maintaining friendship, because both need care, kindness and love to blossom. We must understand that as we move on this planet, every living thing, even the smallest needs its own space. Nothing is free of cost, either hard work, a lot of thought or money are involved in the gift. So we must learn to thank the person, who gives a gift and respect human beings.

Question 2.
What is the importance of human beings on earth?
Answer:
Every human being is unique. He/she deserves to be respected. When one is forgotten by the other, it makes him feel very sad. Every person makes a difference in life and his presence is needed. We must never put anyone to shame and no one has the authority to make others feel bad about themselves. We must respect and treat everyone well and be considerate towards others.

Lesson in Life Summary

In the poem Lessons in life the poets Daniel Ho and Bridgette Bryant bring out the importance of friendship in life and they add value to it by comparing it to the episode of planting flowers.

Just like making a flower bloom, friendship also blossoms only when there is constant care, love and kindness showered on them for a long period of time. Lessons that are taught by life come out of facing great difficulty. Similarly every small gift has a great deal of effort behind it. One should respect it and never forget to say ‘thank you’. We feel sad when we are forgotten by others and similarly others feel sad when they are forgotten. Everyone is unique and no one must be put to shame.

The poets repeat the values of gratitude, love and respect in the final stanza to make everyone understand that without these, no one can live happily. Hence happy friendship blossoms and planting flowers bloom only with love and kindness reciprocated.

Students can Download Social Science Geography Term 3 Chapter 2 Exploring Continents (Africa, Australia and Antarctica) Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Social Science Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Social Science Geography Solutions Term 3 Chapter 2 Exploring Continents (Africa, Australia and Antarctica)

Samacheer Kalvi 8th Social Science Geography Exploring Continents (Africa, Australia and Antarctica)Textual Evaluation

I. Choose the best answer:

Question 1.
The southernmost tip of Africa is …………..
(a) Cape Blanca
(b) Cape Agulhas
(c) Cape of Good Hope
(d) Cape Town
Answer:
(b) Cape Agulhas

Question 2.
The manmade canal through an isthmus betw een Egypt and Sinai Peninsula is
(a) Panama Canal
(b) Aswan Canal
(c) Suez Canal
(d) Albert Canel
Answer:
(c) Suez Canal

Question 3.
In respect of the Mediterranean climate, consider the following statements and choose the correct answer.
(1) The average rainfall is 15 cm
(2) The summers are hot and dry; winters are rainy.
(3) Winters are cool and dry; Summers are hot and wet
(4) Citrus fruits are grown
(a) 1 is correct
(b) 2 and 4 are correct
(c) 3 and 4 are correct
(d) All are correct
Answer:
(b) 2 and 4 are correct

Question 4.
The range which separates the west and east flowing rivers in Australia is
(a) Great Dividing Range
(b) Himalayan range
(c) Flinders range
(d) Mac Donnell range
Answer:
(a) Great Dividing Range

Question 5.
Kalgoorile is famous for …………….. mining.
(a) Diamond
(b) Platinum
(c) Silver
(d) Gold
Answer:
(d) Gold

II. Fill in the Blanks:

1. Atlas Mountain is located in …………….. continent.
2. …………….. is the first Indian research station in Antarctica.
3. ………….. is the highest peak of Africa.
4. A temperature grass land of Anustralia is called …………..
5. ………….. is the first indian research station in Antarctica.

Answer:

1. North – west Africa
2. Mt. Kilimanjaro
3. Eucalyptus
4. Downs
5. Dakshin Gangotri

II. Match the following:

1. Pinnacle – Equatorial forest
2. Krill – salt lake
3. Ostrich – small red fish
4. Lake Eyre – flightless bird
5. Jewel of the earth – Pointed limestone pillars

Answer:

1. Pinnacle – Pointed limestone pillars
2. Krill – small red fish
3. Ostrich – flightless bird
4. Lake Eyre – salt lake
5. Jewel of the earth – Equatorial forest

IV. Let us learn:

Question 1.
Assertion (A) : Aurora is a curtain of color lights appear in the sky.
Reason (R): They are caused by magnetic storms in the upper atmosphere.
(a) Both A and R are individually true and R is the correct explanation for A.
(b) Both A and R are individually true but R is not the correct explanation for A
(c) A is true but R is false.
(d) R is true but A is false
Answer:
(a) Both A and R is individually true and R is the correct explanation for A

Question 2.
Assertion (A) : A geological feature of Africa is the Great Rift Valley.
Reason (R): A Rift valley is a large crack in the earth’s surface formed by tectonic activity.
(a) Both A and R is individually true and R is the correct explanation for A.
(b) Both A and R are individually true but R is not the correct explanation for A
(c) A is true but R is false.
(d) R is true but, A is false
Answer:
(a) Both A and R is individually true and R is the correct explanation for A

V. Answer in brief:

Question 1.
Why Africa is called a “Mother Continent”?
Answer:
Africa is nicknamed as the ‘Mother Continent’ as it was the oldest inhabited continent on Earth.

Question 2.
What are the important rivers of Africa?
Answer:
The important rivers of Africa are R. Nile, R. Congo or Zaire, R. Niger, R. Zambezi, R. Orange and R. Limpopo.

Question 3.
Name the physical division of Australia.
Answer:
The Physical divisions of Australia are –

1. The Great Western Plateau
2. The Central Low lands
3. The Eastern High lands

Question 4.
Write about the nature of Antarctica continent.
Answer:

1. Antarctica is a unique continent. It does not have a native population.
2. There is no country in Antarctica.
3. It is the coldest continent with a permanent cover of ice.
4. It is the only continent called white continent.

Question 5.
Mention any four economic activities of Australia.
Answer:
Agriculture, forestry, fishing mining, manufacturing, trade and services are the major economic activities of Australia.

VI. Distinguish between:

Question 1.
Sahel and Sahara
Answer:
1. Sahel:

• Sahel is a semi-arid tropical Savanna region.
• It covers an area of 3.0 million sq km.
• It is largely a semi-arid belt of barren, sandy and rocky land.

2. Sahara:

• The world-famous Sahara desert is located in the northern part of Africa.
• It has an area of .9.2 million sq kms.
• It consists of many topographical features such as Mountain, plateaus, ergs, oases, sand and gravel covered plains, salt flats, basins and depressions.

Question 2.
Western Antarctica and Eastern Antarctica.
Answer:
1. Western Antarctica:

• The West Antarctica faces the Pacific Ocean.
• The Antarctic Peninsula which points towards the South America shows that it is the continuation of the Andes mountain range.

2. Eastern Antarctica:

• The East Antarctica faces the Atlantic and the Indian Oceans.
• The Mt. Erebus in this region is an active volcano located in the Ross Island.

Question 3.
Great Barrier Reef and Artesian Basin.
Answer:
1. Great Barrier Reef:

• Great Barrier Reef is located in the north east of Australia.
• It is formed by the tiny coral polyps..
• It is about 2300 kms long.

2. Artesian Basin:

• The Artesian Basins are regions on the earth’s surface where water gushes out like a fountain.
• It is found in the arid and semi – arid parts of Queensland.
• It extents for 1.7 million square km.

VII. Give reasons:

Question 1.
Egypt is called the gift of the Nile.
Answer:

1. Nile is the life line of Egypt
2. Without Nile the Egypt would have been a desert
3. So Egypt in the gift of the Nile.

Question 2.
Deserts are found in the western margins of continents.
Answer:

1. Most of the world deserts are located in the western margins of continents in the subtropics because the prevailing winds in the tropics are tropical easterly winds.
2. The tropical easterly winds become dry by the time they reach the western margins of continent and so they bring no rainfall.

Question 3.
Antarctica is called the continent of scientists.
Answer:

1. Scientists of any country are free to conduct experiments and collect data from Antarctica.
2. Hence it is called ‘continent of Science’.

VIII. Answer in a paragraph each:

Question 1.
Give an account on mineral wealth of Australia.
Answer:

1. Minerals are the largest export item of Australia.
2. It contributes about 10 percent of country’s GDP.
3. Australia is the world’s leading producer of bauxite, limonite, rutile and zircon.
4. The Second largest producer of gold, lead, lithium, manganese ore and zinc, the third largest producer of iron ore and uranium and they fourth largest producer of black coal.
5. The coal belts of the country stretches from New Castle to Sydney on the South Eastern Coast.
6. Iron ores are found mainly in southern and Western Australia.
7. Petroleum and natural gas is obtained from Bass Strait and west of Brisbane.
8. Uranium is mined in northern territory at Ram jungle and Queensland.
9. Gold is mined in the western desert at Kalgoorlie and Koolgarlie.
10. Lead, Silver, Zinc, Manganese, Tungsten, Nickel and copper are also mined in parts of Australia.

Question 2.
Describe the flora and fauna of Antarctica
Answer:
Flaora and Fauna:

1. Since the temperature is below freezing point almost throughout the year, no major vegetation is found in this continent.
2. Simple plants like algae, mosses, liverworts, lichens and microscopic fungi can survive and grow in Antarctica.
3. Some algae live in the snow, while other plants grow on the coastal rocky land that is ice free.
4. A few species of plants, such as plankton, algae and mosses are seen in and around, Antarctica’s fresh and saltwater lakes.
5. Small red fish called krill are found in large shoals .It is the food for many warm blooded sea animals.
6. The blue whale is the largest animal which feeds on plankton. All these animals and birds have a thick layer of fat called blubber which helps them to withstand the cold condition.
7. Penguin birds in Antarctica cannot fly. They have webbed feet and flipper instead of wings. Small invertebrates are the only land animals which lives in the continent.

Question 3.
Name the physical divisions of Africa and explain any one.
Answer:
1. Africa consists of mixture of land forms such as mountains, plateaus and plains. The following are the 8 major physical divisions of Africa.

• Sahara
• Sahel
• Savanna
• The Great Rift Valley and the Great Lakes of Africa
• East African Highlands
• Swahili Coast
• The Congo Basin or Zaire Basin
• Southern Africa

2. Southern Africa.

• Most part of the Southern Africa is a plateau region.
• Drakensberg Mountain is found in the eastern portion of the escarpment.
• It extends from north east to south west for 1125 km.
• Its highest peak is.Thabana Ntlenyana (3482m).
• This region is covered with grasslands known as‘Veld’.
• Kalahari Desert lies in the south and Namib Desert is along the south -west shore of Africa.
• Kalahari Desert in this region is not actually a desert but, a bushy scrubland situated between the Orange and Zambezi Rivers.

XI. Map skill:

Question 1.
Mark the following on the outline map of Africa and Australia.
Answer:
Africa:
Equator, Atlas Mountain, Sahara, Eastern highlands, Mediterranean Sea, Atlantic Ocean, Indian Ocean, Suez Canal, Mount Kilimanjaro,

Australia:
Great Dividing Range , Great barrier reef, Tasmania, tropic of Capricorn, pacific ocean. Great Australian Sandy Desert. Indian ocean, Sydney, Canberra.

X. Activity:

Question 1.
Find out the hemisphere and season during December for the following countries.
Answer:

Question 2.
Label the name of the different states of Australia in the following map

Answer:

Samacheer Kalvi 8th Social Science Geography Chapter 2 Exploring Continents (Africa, Australia and Antarctica) Additional Questions

I. Choose the correct answer:

Question 1.
The second largest continent of the world is …………..
(a) Asia
(b) Africa
(c) Europe
(d) South Africa
Answer:
(b) Africa

Question 2.
The only continent through which Tropic of Capricorn and Tropic of Cancer pass is ………….. in Indian ocean took place in the year 2004.
(a) Asia
(b) Australia
(c) Africa
(d) Europe
Answer:
(c) Africa

Question 3.
Africa is located in all the ………….. hemisphere.
(a) three
(b) two
(c) four
(d) none of the above
Answer:
(c) four

Question 4.
Henry M. Stanley used the term ………….. to refer to Africa
(a) Land of rising sun
(b) Land of Thousand lakes
(c) Dark continent
(d) none of the above
Answer:
(c) Dark continent

Question 5.
The continent of Africa consists of ………….. countries.
(a) 48
(b) 54
(c) 36
(d) 60
Answer:
(b) 54

Question 6.
The term ‘Maghreb’ refers to ………….. of Africa.
(a) North Western countries
(b) West part
(c) Central part
(d) Eastern part
Answer:
(a) North Western countries

Question 7.
Sahara desert is located in the ………….. part of Africa.
(a) Eastern
(b) Western
(c) Southern
(d) Northern
Answer:
(d) Northern

Question 8.
The Mediterranean Sea and Atlantic ocean are separated by ………….. moutain.
(a) Atlas
(b) Himalayas
(c) Rocky
(d) None of the above
Answer:
(a) Atlas

Question 9.
The African Great Lakes consist of ………….. major lakes.
(a) 5
(b) 7
(c) 6
(d) 4
Answer:
(b) 7

Question 10.
Kalahari desert situated between the Orange and ………….. Rivers.
(a) Nile
(b) Congo
(c) Amazon
(d) Zambezi
Answer:
(d) Zambezi

Question 11.
Father of African rivers is …………..
(a) Cango
(b) Nile
(c) Niger
(d) Zambezi
Answer:
(b) Nile

Question 12.
Southern Africas ‘River of Life’ is …………..
(a) Cango
(b) Zambezi
(C) Nile
(d) Zaire
Answer:
(b) Zambezi

Question 13.
The Chief cash crop of Africa is …………..
(a) Cotton
(b) Jute
(c) Tea
(d) Sugarcane
Answer:
(a) Cotton

Question 14.
Australia’s largest physical division is …………..
(a) The Great Western Plateau
(b) The Central Low lands
(c) The Eastern High lands
(d) None of the above
Answer:
(a) The Great Western Plateau

Question 15.
Mt. Kosciuszko is located in the …………..
(a) Melbourne
(b) Perth
(c) New South Wales
(d) Adelaide
Answer:
(c) New South Wales

Question 16.
Tasmania gets rain throughout the year from …………..
(a) Trade winds
(b) Monsoon winds
(c) westerly winds
(d) None of the above
Answer:
(c) westerly winds

Question 17.
The Cash Crop of Australia is …………..
(a) Cotton
(b) Tea
(c) Wool
(d) Jute
Answer:
(c) Wool

Question 18.
Australia is highly dependent on ………….. transport.
(a) road
(b) train
(c) air
(d) water
Answer:
(a) road

Question 19.
There is no native population in …………..
(a) Asia
(b) Africa
(c) Australia
(d) Antarctica
Answer:
(d) Antarctica

Question 20.
Artesian basins are common in …………..
(a) Africa
(b) Australia
(c) Antarctica
(d) South America
Answer:
(b) Australia

II. Fill in the blanks:

1. The second most populous continent after Asia is …………..
2. In Africa the Prime Meridian Passes near ………….. the capital of Ghana.
3. The major island of Africa is ……………
4. Sahara is one of the largest ………….. in the world.
5. ………….., an extinct volcano in chad, is the highest point in the sahara.
6. Sahara’s deepest point is ………….. in Egypt.
7. Sahel means ……………
8. In Africa tropical dry grasslands are known as …………..
9. One of the largest plains in Savanna is …………..
10. ………….. plain is called the open Air Zoo.
11. The largest fresh water body in Africa is …………..
12. The first largest fresh water is ………….. in USA.
13. Lake Victoria is the source of river …………..
14. The longest and deepest fresh water lake in the world is ……………
15. Swahili coast is located along the shores of ……………
16. The world’s first largest river basin is ………….. in South America.
17. The second largest river basin in the world is the ………….. in Africa.
18. Southern Africa region is c covered with grasslands known as ……………
19. The Gift of the Nile is ……………
20. The longest river in the world is ……………
21. The world famous waterfall Victoria is formed by the river ……………
22. Southern Africa’s ‘River of Life’ is river ……………
23. A hot and dry dusty local wind blowing from the Sahara desert to Guinea coast is called …………..
24. A hot local wind blowing from Sahara to Mediterranean Sea is called …………..
25. Ghana is the Chief Producer of ……………
26. The most populous country of Africa is …………..
27. Australia is the largest ………….. and smallest ………….. in the world
28. Australia was discovered by …………. an English Seaman in 1770 .
29. The Tropic of ………….. cuts the Australia continent into two equal halves.
30. The capital of Australia is ……………
31. ………….. is the largest monolith rock in the world.
32. The largest desert in Australia is the ……………
33. The largest Salt Lake ………….. lies in the central low lands of Australia.
34. The Eastern Highlands are also known as ………….. in Australia.
35. The Great. Barrier Reef is formed by the ……………
36. The longest river in Australia is ……………
37. The plants and trees in Australia are called ……………
38. The people who work in the sheep station in Australia are known as ……………
39. The indigenous people of Australia are called …………..
40. Tasmania is known as the ………….. Island.
41.  ………….. are rearing in Southern Australia.
42.  The densely populated region is ………….. part of Australia.
43. The Mt. Erebus an active volcano is located in the ………….. Island.
44. The largest piece of ice on the surface of Earth is …………..
45. The largest glacier in the world in ………….. located in …………..

Answers:

1. Africa
2. Accra
3. Antarctica
4. hot deserts
5. Mount Koussi
6. Qattara
7. broder or margin
8. savanna
9. Serengeti
10. Serengeti
11. Lake Victoria
12. Lake superior
13. Nile
14. Tanganyika
15. East Africa
16. Amazon
17. Congo
18. Veld
19. Egypt
20. River Nile
21. Zambezi
22. Zambezi
23. Harmattan
24. Sirocco
25. Cocoa
26. Nigeria
27. island/continent
28. Captain James Cook
29. Capricorn
30. Canberra
31. Ayers rock or Uluru
32. Great Victoria Desert
33. Lake Eyre
34. Great Dividing Range
35. Tiny coral polyps
36. River Murray
37. Xerophytes
38. Jackroos
39. Aborigines
40. Apple
41. Merino
42. Southeastern
43. Ross
44. Antarctica
45. Lambert glacier, Antarctica

III. Match the following:

Question 1.

1. Dark Continent – a) Explorer
2. David Livingstone – b) Evergreen Forest
3. Atlas mduntain – c) Sheep rearing
4. Congo Basin – d) Africa
5. Karoo – e) Young fold mountain

Answer:

1. d
2. a
3. e
4. b
5. c

Question 2.

1. Captain James Cook – a) New South Wales
2. Uluru – b) Australian river
3. Mt. Kosciuszko – c) Swamp forests
4. Lachlan – d) Monolitic rock
5. Melaleuca – e) Australia

Answer:

1. e
2. d
3. a
4. b
5. c

Question 3.

1. Antarctica – a) largest animal
2. White continent – b) Largest Research station
3. Blue whale – c) India
4. Mcmurdo – d) Continent of Science
5. Bharathi – e) Antarctica

Answer:

1. d
2. e
3. a
4. b
5. c

IV. Let us learn :

Question 1.
Assertion (A) : H.M. Stanley called Africa Dark continent.
Reason (R) : In the beginning the interior of Africa was largely unknown to people.
(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually true and R is not the correct explanation of A
(c) A is true but R is false
(d) R is true but A is false
Answer:
(a) Both A and R are individually true and R is the correct explanation of A

Question 2.
Assertion (A) : The great Barrier Reef is one of the natural wonders of the world.
Reason (R) : The Great Barrier Reef is formed by the tiny coral polyps.
(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually true and R is not the correct explanation of A
(c) A is true but R is false
(d) R is true but A is false
Answer:
(a) Both A and R are individually true and R is the correct explanation of A

V. Answer in brief :

Question 1.
Explain the term‘Maghreb’.
Answer:
The north-western African countries of Morocco, Algeria, Libya, Mauritania and Tunisia are collectively called ‘Maghreb’, which means west in Arabic language.

Question 2.
Write a note on Atlas Mountains.
Answer:

1. Atlas Mountain lies in the north- west of Africa.
2. It is a young fold mountain.
3. It separates the Mediterranean sea and Atlantic ocean.
4. The highest point is Mount Toubkal (4167m).

Question 3.
Where do we find Savanna grasslands in Africa?
Answer:

1. Savanna grassland is found in the regions just north and south of the rain forests that lie along the equator.
2. Trees are the main features of the landscape in some parts of the savanna, while tall grass covers the other areas.
3. The Serengeti Plain is one of the largest plains in Savanna.
4. This is called the ‘Open Air Zoo’.

Question 4.
Nile is known as the Father of African Rivers. Give reasons.
Answer:

1. River Nile is known as the Father of African Rivers.
2. It is the largest river in the world with a length of 6650 km.
3. White Nile and the Blue Nile join together to form the River Nile at Khartoum, in Sudan.
4. It flows towards and drains into the Mediterranean-sea.

Question 5.
Write about the animals of Africa.
Answer:

1. There are over one million species of animals in Africa including both the heaviest (elephants) and the tallest (giraffes) land animals on the earth.
2. White Rhinoceros, Western Green Mamba, Zebra, African Elephants, chimpanzee, gorilla, Hippopotamus and Giraffe are the major animals of Africa.
3. Bonobo, Wild Dogs, hyena and Lemur are the typical animals of Africa.

Question 6.
Name the major tribes of Africa.
Answer:
Afar, Fatwa, Bushmen, Dinka, Masai, Pygmies, Zulu, Tswan, and Efe are the major tribes of Africa.

Question 7.
Mention the political division of Australia.
Answer:
There are six states and two Union Territory in Australia They are:

1. New South Wales
2. Queensland
3. South Australia
4. Tasmania
5. Victoria
6. Western Australia
7. Northern Territory
8. Capital Territory (Canberra).

Question 8.
Mention the important cities of Australia.
Answer:

1. Canberra is the capital of Australia.
2. Sydney, Brisbane, Adelaide, Hobart, Melbourne, Perth and Darwin are the other important cities of Australia.

Question 9.
Why is Ayers rock one of the natural wonders of Australia?
Answer:

1. Ayers rock or Uluru is the largest monolith rock in the world.
2. It is found in the central part of The Great Western Plateau region.
3. It is 863 meters high above the sea level.
4. The pointed limestone pillars called Pinnacles are common in this region.

Question 10.
What is meant by Xerophytes?
Answer:

1. The plants and trees in Australia are adapted to dry conditions.
2. They can survive for long period without water.
3. They are called Xerophytes.

Question 11.
Write about the fauna of Australia.
Answer:

1. Australia has almost 400 mammal species and about 140 species of marsupials.
2. These are the animals that carry their young ones in their pouches.
3. Kangaroo is the national animal of Australia.
4. Koala, platypus Wallaby and Dingo are the other important animals of Australia.
5. The bird species like the laughing kookaburra, emu, and rainbow lorikeet are the major birds of Australia.

Question 12.
What are Merino sheep.
Answer:

1. In Australia sheep farming is common in the temperate grassland.
2. Merino sheep are rearing in southern Australia, Tasmania, Victoria and New South Wales.
3. Sheep industry is a well developed industry in Australia.
4. The wool is described as the ‘Cash Crop’ in Australia.

Question 13.
Mention the important industries A frica.
Answer:

1. Food and beverage manufacturing industry is the primary industry in Australia.
2. Finance, ship building, information and technology, mining, insurance, aviation and telecommunication industries are the other important industries.

Question 14.
Mention the living creatures of Antarctica Continent.
Answer:

1. Small red fish called krill are found in large shoals .It is the food for many warm blooded sea animals.
2. The living creatures of this region are includes whales, seals, walrus and sea birds like penguins, albatross, polar Skua and Stout.
3. The blue whale is the largest animal which feeds on plankton.

VI. Distinguish between:

Question 1.
River Congo and River Niger
Answer:
1. River Congo:

• It is the second largest river of Africa.
• Its rises in the highlands of North Eastern Zambia .
• Its length is about 4700km.
• Drains into the Atlantic Ocean

2. River Niger:

• It is one of the major rivers in West Africa.
• It rises from the highlands of Guinea.
• It flows for about 4184 km.
• Drains into the Gulf of Guinea on the Atlantic Ocean.

Question 2.
Equatorial climate and Mediterranean climate (Africa).
Answer:
1. Equatorial climate (Africa):

• It is found in the equatorial region covering the Congo River basin and east African highlands.
• Temperature and rainfall are high all the year round in this region.

2. Mediterranean climate (Africa):

• It is found in the north-western and south western tips of Africa.
• These regions get rainfall in winters while in summers it is hot and dry.

Question 3.
Waterways and Airways (Africa).
Answer:
1. Waterways (Africa):

• Africa has trade routes between Asia and Australia in the east, Europe in the north and America in’the west.
• The major sea ports of Africa are Durban, Dar es Salaam and Mogadishu on the Indian Ocean, Port Said, and Alexandria, on the Mediterranean Sea, Cape Town, Algiers and Abidjan on the Atlantic Ocean.

2. Airways (Africa):

• They connect the capital cities of Africa and the other parts of the world.
• The major international airports of the continent are Cairo, Johannesburg, Nairobi, Dakar, Addis- Ababa, Casablanca, Durban, Douala and Logos.

VII. Give Reasons :

Question 1.
Kilimanjaro summit will be ice -free by 2025.
Answer:

1. The glaciers on the top of Kilimanjaro have been disappearing since 20th centuries.
2. If this trend continues. Kilimanjaro summit will be .ice -free by 2025.

Question 2.
The name of Swahili to the people of Swahili Coast.
Answer:

1. Swahili Coast region extents from Somalia to Mozambique.
2. It was a region where the Africans and Arabs mixed to create a unique culture referred to as Swahili Culture.
3. People of this coast are also called as ‘Swahili’.

Question 3.
Roadways and Railways in Africa are poorly developed.
Answer:

1. Roadways and Railways in Africa are poorly developed due to the presence of many barriers.
2. It is very difficult to lay the roads and rails across the deserts and the dense forests.
3. South Africa, Kenya, Egypt, Libya. Morocco and Nigeria have roadways and railways to some extent.

Question 4.
Australia was the last continent to be discovered.
Answer:

1. Australia was the last of all the continents to be discovered.
2. It was due to its remoteness.

Question 5.
Antarctica is the coldest continent.
Answer:

1. Antarctica is the coldest continent in the world.
2. It is located in the polar region.
3. It has a permanent cover of ice.

Question 6.
Antarctica is the only white continent.
Answer:

1. Antarctica is the only continent called white continent.
2. It has a permanent cover of ice.
3. In some places its ice cap is 4,000 metres deep.

Question 7.
The extraction of minerals does not take place in Antarctica.
Answer:

1. The international agreement on the continent of Antarctica does not permit the extraction of minerals.
2. Hence the extraction of minerals does not take place.

VIII. Answer in a paragraph each :

Question 1.
Write about the mineral wealth of Antarctica Continent.
Answer:

1. Scientific studies show that the Antarctic continent is to be rich in gold, platinum, nickel, copper and petroleum.
2. Traces of chromium, lead, molybdenum, tin, uranium, and zinc are also seen.
3. The possible resources of this region also include silver, platinum, iron ore, cobalt, manganese and titanium.
4. Coal and hydrocarbons have been explored in minimal non-commercial quantities.

Question 2.
Explain the term Aurora
Answer:

1. A natural Curtain of combination of bright pink, red and green color light that appears in the sky near the north and south magnetic poles is called Aurora.
2. The effect is caused by the interaction of charged particles from the sun with atoms in the upper atmosphere.
3. It is also called Aurora Australis or Southern Lights in the South Pole and Aurora Borealis or Northern Lights in the North Pole.
4. These amazing colours appear in the earth’s sky, especially in the high latitudinal countries like Alaska in the north and New Zealand of Falkland in the south.

Question 3.
What type of climatic Pattern is experienced by Australia?
Answer:

1. Australia contains the second largest area of extremely arid land in the world.
2. The Tropic of Capricorn divides the Australia into two equal parts.
3. The Northern half is in the warm tropical zone and the southern half is in the cool temperate zone.
4. The north coastal region experiences monsoon type of climate and there is a heavy rainfall during summer.
5. The east coastal region receives good rainfall from south east trade wind.
6. The hot desert climate extends from central lowlands to western shores.
7. The rainfall in this region is less than 25cm per annum.
8. Mediterranean type of climate prevails in the southern tip of Australia in the region around Perth and Adelaide.
9. Tasmania gets rain throughout the year from westerly winds.

Question 4.
Explain the location and size of Africa.
Answer:

1. Africa is the second largest and second most populous continent after Asia.
2. It stretches from 37°21 ’North latitude to 34° 51 ’ South latitude and from 17°33’ West longitude to 51 °27 ’ East longitude.
3. It spreads over an area of about 30.36 million square kilometres (20.2% of the world’s land area).
4. The equator passes through the middle of Africa and cuts into two equal halves.
5. It is the only continent through which the major latitudes such as Tropic of Cancer, Equator and Tropic of Capricorn pass.
6. Its north-south extent is 7623 km and east-west extent is 7260 km.
7. The Prime Meridian passes this continent.
8. Africa is located in all the four hemispheres.

Samacheer Kalvi 8th Social Science Geography Chapter 2 Exploring Continents (Africa, Australia and Antarctica) Intext activity

Question 1.
On the outline map of Africa draw the courses of main rivers and name them.
Answer:

Question 2.
There are eight deserts in Australia. List them out with the help of Atlas.
Answer:

1. Central Desert
2. Gibson Desert
3. Great Sandy Desert
4. Great Victoria Desert
5. Little Sandy Desert
6. Simpson Desert
7. Strzelecki Desert
8. Tanami Desert

Students can Download Maths Chapter 1 Life Mathematics Ex 1.1 Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 1 Chapter 1 Life Mathematics Ex 1.1

Question 1.
Fill in the blanks:

Question (i)
If 30% of x is 150, then x is ………….
Answer:
500
Hint:
Given 30% of x is 150

Question (ii)
2 minutes is ………… % to an hour.
Answer:
3\(\frac{1}{3}\)%
Hint:
Let 2 min be x% of an hour
and 1 hr = 60 min
x% = \(\frac{2}{60}\) x 100 = \(\frac{200}{3}\) = \(\frac{10}{3}\) = 3\(\frac{1}{3}\)
x = 3\(\frac{1}{3}\)

Question (iii)
If x % of x = 25, then x = …………
Answer:
50
Hint:
Given that x % of x is 25
∴ \(\frac{x}{100}\) = 25
x² = 25 x 100 = 2500
∴ x = \(\sqrt{2500}\) = 50

Question (iv)
In a school of 1400 students, there are 420 girls. The percentage of boys in the school is ………….
Answer:
70
Hint:
Given total number of students in school = 1400
Number of girls in school = 420
Number of boys in school = 1400 – 420 = 980

% of boys = 70%

Question (v)
0.5252 is ………….. %.
Answer:
52.52%
Hint:
Given a number, and to express as a percentage, we need to multiply by 100
∴ to express 0.5252 as percentage, we should multiply by 100
∴ 0.5252 x 100 = 52.52%

Question 2.
Rewrite each underlined portion using percentage language.

Question (i)
One half of the cake is distributed to the children.
Answer:
Answer:
50% of the cake is distributed to the children
Hint:
One half is nothing but \(\frac{1}{2}\) as percentage, we need to multiply by 100
\(\frac{1}{2}\) x 100 = 50%

Question (ii)
Aparna scored 7.5 points out of 10 in a competition.
Answer:
Aparna scored 75% in a competition
Hint:
7.5 points out of 10 is \(\frac{7.5}{10}\) = 0.75
For percentage, we need to multiply by 100
∴ We get 0.75 x 100 = 75%

Question (iii)
The statue was made of pure silver.
Answer:
96% students participated in sports
Hint:
Pure silver means there are no other metals
so, 100 out of 100 parts is made of silver = \(\frac{100}{100}\)
∴ to express as percentage, \(\frac{100}{100}\) x 100% = 100%

Question (iv)
48 out of 50 students participated in sports
Answer:
96% students participated in sports
Hint:
48 out of 50 students in fraction form is \(\frac{48}{50}\).
As a percentage, we need to multiply by 100

Question (v)
Only 2 persons out of 3 will be selected in the interview
Answer:
Only 66\(\frac{2}{3}\)% persons will be selected in the interview.
Hint:
2 out of 3 in fraction form is \(\frac{2}{3}\) to express as percentage, we need to multiply by 100
\(\frac{2}{3}\) x 100 = \(\frac{200}{3}\) = 66\(\frac{2}{3}\)%

Question 3.
48 is 32% of what number?
Solution:
Let the number required to be found be ‘x’
Given that 32% of x is 48

Question 4.
A bank pays ₹ 240 as interest for 2 years for a sum of ? 3000 deposited as savings. Find the rate of interest given by the bank.
Solution:
The formula for simple interest is given by
Interest (I) = \(\frac{PxRxT}{100}\) 100
Where P is principal amount; R is rate of interest in percentage; t is time period Substituting given values in formula, we get
P = 3000, t = 2 yrs, I = Rs 240

Question 5.
A Welfare Association has a sports club where 30% of the members play cricket, 28% play volleyball, 22% play badminton and the rest play indoor games. If 30 member play indoor games.

1. How many members are there in the sports club?
2. How many play cricket, volleyball and badminton?

Solution:
Given data
Members who play Cricket = 30% …..(1)
Members who play Vollyball = 28% …..(2)
Members who play Batminton = 22% ……(3)
Members who play outdoor games = (1) + (2) + (3) = 30
Members who play indoor games = 100 – 80 = 20%
Also given 30 members play indoor games
Let total no of members be ‘x’
∴ \(\frac{30}{x}\) = 20
∴ x = \(\frac{30×100}{20}\) = 15

1. Total number of members is 150

2. Members who play Cricket = 30% of total = \(\frac{30}{100}\) x 150

Question 6.
What is 25% of 30% of 400?
Solution:
Required to find 25% of 30% of 400

Question 7.
If the difference between 75% of a number and 60% of the same number is 82.5, then find 20% of the number.
Solution:
Given that 75% of number less 60% of number is 82.5. Let the number be ‘x’
∴ \(\frac{75}{100}\) × x = 82.5
∴ 0.75 – 0.6.60x = 82.5
∴ 0.15x = 82.5
∴ x = \(\frac{82.5}{0.15}\) = \(\frac{8250}{15}\) = 550
Required to find 20% of number ie 20% of x.

Question 8.
If a car is sold for ₹ 2,00,000 from its original price of? 3,00,000 find the percentage for decrease in the value of the car.

Solution:
Original price of car = ₹ 3,00,000
actual selling price of car = ₹ 2,00,000
Decrease in amount from original = 3,00,000 – 2,00,000 = 1,00,000

Question 9.
A number when increased by 18% gives 236. Find the number.
Solution:
Let the number be x. Given that when it is increased by 18%, we get 236.
x + \(\frac{18}{100}\) = 236
\(\frac{100x+18x}{100}\) = 236
\(\frac{118}{100}\)x = 236
The number = x = \(\frac{236×100}{118}\) = 200

Question 10.
A number when decreased by 20% gives 80. Find the number.
Solution:
Let the number be x. Given that when it is increased by 20% we get 80.

Question 11.
A number is increased by 25% and then decreased by 20%. Find the change in that number.
Solution:
Method 1:
Let the number be x. First it is increased by 25%

Method 2:
[to understand, let us assume that number is 100]
So, first when we increase by 25%, we get

We get back 100 ⇒ No change

Question 12.
If the numerator of a fraction is increased by 25% and the denominator is increased by 10%, it becomes \(\frac{2}{5}\). Find the original fraction.
Solution:
Let the fraction be \(\frac{N}{D}\) where N is numerator & D is denominator
It is given that numerator is include by 25%

Question 13.
A fruit vendor bought some mangoes of which 10% were rotten. He sold 33 \(\frac{1}{3}\)% of the rest. Find the total number of mangoes bought by him initially, if he still has 240 mangoes with him.

Solution:
Let the number of mangoes bought by fruit seller initially be x.
Given that 10% of mangoes were rotten
∴ Number of rotten mangoes = \(\frac{10}{100}\) × x
Number of good mangoes = x – no. of rotten mangoes
= x – \(\frac{10}{100}\)x = \(\frac{100x-10x}{100}\) = \(\frac{90}{100}\)x …(1)
Number of mangoes sold = 33\(\frac{1}{3}\)% of good mangoes = \(\frac{100}{3}\)%
∴ Mangoes sold = \(\frac{100}{3}\) x \(\frac{90}{100}\)x × \(\frac{1}{100}\) = \(\frac{30}{100}\)x
Number of mangoes remaining = No. of good mangoes – No. of mangoes sold
From (1) and (2)

Question 14.
A student gets 31% marks in an examination but fails by 12 marks. If the pass percentage is 35%, find the maximum marks of the examination.
Solution:
Let the maximum marks in the exam be ‘x’. Pass percentage is given as 35%
∴ Pass mark = \(\frac{35}{100}\) × x = \(\frac{35}{100}\)x
Student gets 31 % marks = \(\frac{31}{100}\) × x = \(\frac{31}{100}\)x
But student fails by 12 marks → meaning his mark is 12 less than pass mark.
∴ \(\frac{31}{100}\)x = \(\frac{35}{100}\)x – 12
∴ \(\frac{35}{100}\)x – \(\frac{31}{100}\)x = 12
∴ \(\frac{35x-31x}{100}\) = 12 ⇒ \(\frac{4x}{100}\) = 12
∴ \(\frac{12×100}{4}\) = 300

Question 15.
The ratio of boys and girls in a class is 5:3. If 16% of boys and 8% of girls failed in an examination, then find the percentage of passed students.
Solution:
Let number of boys be ‘6’ and number of girls be ‘g’
Ratio of boys and girls is given as 5:3
b:g = 5:3 ⇒ \(\frac{b}{g}\) = \(\frac{5}{3}\) …..(A)
Failure in boys = 16% = \(\frac{16}{100}\) x b = \(\frac{16b}{100}\)
Failure in girls = 8% = \(\frac{8}{100}\) x g = \(\frac{8g}{100}\)
Pass in boys = 100 – 16% = 84% \(\frac{84}{100}\)b …..(1)
Pass in girls = 100 – 8% = 92% = \(\frac{92}{100}\)g
From A, we have \(\frac{b}{g}\) = \(\frac{5}{3}\), = adding 1 on both sides, we get
\(\frac{b}{g}\) + 1 = \(\frac{5}{3}\) + 1
\(\frac{b+g}{g}\) = \(\frac{5+3}{3}\) = \(\frac{8}{3}\)
∴ g = \(\frac{3}{8}\)(b + g)
Similarly b = \(\frac{5}{8}\)(b + g)
Total pass = Pass in girls + Pass in boys
= (1) + (2) = \(\frac{84}{100}\)b + \(\frac{92}{100}\)g

Objective Type Questions

Question 16.
12% of 250 litres is the same as ………. of 150 liters
(a) 10%
(b) 15%
(c) 20%
(d) 30%
Answer:
(c) 20%
Hint:
12% of 250 = \(\frac{12}{100}\) x 250 = 30 lit
Percentage : \(\frac{30}{150}\) x 100 = 20%

Question 17.
If three candidates A, B and C is 3 in a school election got 153, 245 and 102 votes respectively, the percentage of votes for the winner is ……..
(a) 48%
(b) 49%
(c) 50%
(d) 45%
Answer:
(b) 49%
Hint:
Candidate 1: 153
Candidate 2: 245 – winner [as maximum votes]
Candidate 3: 102
Total votes = 1 + 2 + 3 = 153 + 245 + 102 = 500

Question 18.
15% of 25% of 10000 = ………..
(a) 375
(b) 400
(c) 425
(d) 475
Answer:
(a) 375
Hint:
15% of 25% of 10000 is
First let us do 25% of 10,000, which is

Next 15% of the above is \(\frac{15}{100}\) x 2500 = 375

Question 19.
When 60 is subtracted from 60% of a number to give 60, the number is –
(a) 60
(b) 100
(c) 150
(d) 200
Answer:
(d) 200
Hint:
Let the number be ‘x’.
60% of the number is \(\frac{60}{100}\) × x = \(\frac{60x}{100}\)
Given that when 60 is subtracted from 60%, we get 60
i.e \(\frac{60}{100}\)x – 60 = 60
∴ \(\frac{60}{100}\)x = 60 + 60 = 120
∴ x = \(\frac{120×100}{60}\) = 200

Question 20.
If 48% of 48 = 64% of x, then x =
(a) 64
(b) 56
(c) 42
(d) 36
Answer:
(d) 36
Hint:
Given that 48% of 48 48 = 64% of x

You can Download Samacheer Kalvi 8th Science Book Solutions Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Science Solutions Term 1 Chapter 9 Introduction to the Information Age

Samacheer Kalvi 8th Science Solutions Introduction to the Information Age

I. Choose the correct answers

Question 1.
Who is the father of computer?
(a) Martin Luther King
(b) Graham Bell
(c) Charlie Chaplin
(d) Charles Babbage
Answer:
(d) Charles Babbage

Question 2.
Which one of the following is an output device?
(a) Mouse
(b) Keyboard
(c) Speaker
(d) Pendrive
Answer:
(c) Speaker

Question 3.
Which one of the following is an input device?
(a) Speaker
(b) Keyboard
(c) Monitor
(d) Printer
Answer:
(b) Keyboard

Question 4.
Pen drive is ……………. device.
(a) Output
(b) Input
(c) Storage
(d) Connecting cable
Answer:
(c) Storage

Question 5.
Fifth generation computer has ……………… Intelligence.
(a) Transistors
(b) Integrated Circuits
(c) Microprocessor
(d) Artificial Intelligence
Answer:
(d) Artificial Intelligence

II. Match the following

Question 1.

Answer:

1. b
2. e
3. a
4. c
5. d

III. Give short answer

Question 1.
What is a Computer?
Answer:
A Computer is an electronic machine that accepts data, stores and processes data into information.

Question 2.
Name the parts of a computer.
Answer:
Parts of a Computer:

1. Input Unit
2. Central Processing Unit (CPU)
3. Output Unit

Question 3.
What is Hardware and Software?
Answer:
Hardware:

1. Hardware is the parts of a computer which we can touch and feel.
2. Hardware includes Input and Output devices, Cabinet, Hard Disk, Mother Board, SMPS, CPU, RAM, CD Drive and Graphics Card.

Software:

1. Hardware is lifeless without software in a computer.
2. Softwares are programmed and coded applications to process the input information.
3. The software processes the data by converting the input information into coding or programmed language.

Samacheer Kalvi 8th Science Solutions Introduction to the Information Age Additional Questions

I. Choose the correct answer

Question 1.
The main component used for the first generation computers is ……………….
(a) Transistors
(b) Integrated Circuits
(c) Microprocessor
(d) Vacuum Tubes
Answer:
(d) Vacuum Tubes

Question 2.
Artificial Intelligence is the main component of ……………… generation computers.
(a) first
(b) Fifth
(c) Third
(d) Fourth
Answer:
(b) Fifth

Question 3.
Computer performs tasks determined by …………….
(a) Programs
(b) Hardware
(c) Keyboard
(d) Mouse
Answer:
(a) Programs

Question 4.
Light pen is a …………….. device.
(a) Input
(b) Output
(c) Software
(d) None of these
Answer:
(a) Input

Question 5.
……………….. of the mouse is used to move the page up and down.
(a) Scroll Ball
(b) Pointer
(c) Right Click
(d) Left Click
Answer:
(a) Scroll Ball

II. Match the following

Question 1.

Answer:

i. e
ii. c
iii. d
iv. a
v. b

Question 2.

Answer:

i. c
ii. e
iii. a
iv. d
v. b

Question 3.

Answer:

i. c
ii. d
iii. a
iv. b

III. Short Answer

Question 1.
Differentiate input and output device.
Answer:

Question 2.
What is a CPU?
Answer:
CPU is the brain of the Computer. The data is processed in the CPU. Th e CPU has namely three parts.

1. Memory Unit
2. Arithmetic Logic Unit (ALU)
3. Control Unit.

Question 3.
What is control unit?
Answer:
The control unit controls the functions of all the parts of the computer.

Question 4.
Write a note on arithmetic logic unit.
Answer:
Arithmetic and Logic unit performs all the arithmetic computations like addition, subtraction, multiplication and division.

Question 5.
Write briefly about memory unit.
Answer:

1. The memory unit in the computer saves all data and information temporarily.
2. We can classify memory unit into two types namely primary and secondary memory.
3. Memory can be expanded externally with the help of Compact Disk (CD), Pendrive, etc.

Question 6.
Mention the classification of computers.
Answer:
The computers can be classified based on their design, shape, speed, efficiency, working of the memory unit and their applications.

1. Mainframe Computer
2. Mini Computer
3. Micro or Personal Computer
4. Super Computer

Question 7.
What are the types of software?
Answer:
The software is divided into two types based on the process. They are

1. System Software (Operating System)
2. Application software

Question 8.
Give some information on system software.
Answer:

1. System Software (Operating system) is software that makes the hardware devices to process the inputted data and to display the result on the output devices like Monitor.
2. Without the operating systems, computer cannot function on its own.
3. Some of the popular operating system are Linux, Windows, Mac, Android etc.

Question 9.
Write a note on application software.
Answer:

1. Application software is a program or a group of programs designed for the benefit of end user to work on computer.
2. The application programs can be installed in the hard disk for the usage on a particular computer.
3. This type of application program completes one or more than two works of the end user.
4. The following are the examples of application program : Video player, Audio player, Word processing software, Drawing tools, Editing software, etc.

You can Download Samacheer Kalvi 8th Science Book Solutions Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Science Solutions Term 2 Chapter 7 Digital Painting

Samacheer Kalvi 8th Science Digital Painting Text Book Exercises

I. Choose the correct answer

Question 1.
Tux paint software is used to ……………..
(a) Paint
(b) Program
(c) Scan
(d) PDF
Answer:
(a) Paint

Question 2.
Which toolbar is used for drawing and editing controls in tux paint software?
(a) Left Side: Toolbar
(b) Right side : Toolbar
(c) Middle : Tool bar
(d) Bottom : Tool bar
Answer:
(a) Left Side : Toolbar

Question 3.
What is the shortcut key for undo option?
(a) Ctrl + Z
(b) Ctrl + R
(c) Ctrl + Y
(d) Ctrl + N
Answer:
(a) Ctrl + Z

Question 4.
Tux Math software helps in learning the ……………….
(a) Painting
(b) Arithmetic
(c) Programming
(d) Graphics
Answer:
(b) Arithmetic

Question 5.
In Thx Math, Space cadet option is used for ………………
(a) Simple addition
(b) Division
(c) Drawing
(d) Multiplication
Answer:
(a) Simple addition

II. Answer the following Questions

Question 1.
What is Tux Paint?
Answer:
Tux Paint is a free drawing program designed for young childreh.

Question 2.
What is the use of Text Tool?
Answer:
Text tool is used to type texts.

Question 3.
What is the Shortcut key for Save option?
Answer:
Ctrl + S

Question 4.
What is Tux Math?
Answer:
Tux Math is an open source arcade – style video game for learning arithmetic.

Question 5.
What is the use of Ranger?
Answer:
Ranger is used to do addition, subtraction, multiplication and division to ten.

Samacheer Kalvi 8th Science Digital Painting Additional Questions

I. Choose the correct answer.

Question 1.
Which tool is used to open an existing file?
(a) Line
(b) Open
(c) New
(d) Undo
Answer:
(b) Open

Question 2.
What is the shortcut key for print option?
(a) Ctrl + S
(b) Ctrl + O
(c) Ctrl + P
(d) Ctrl + Y
Answer:
(c) Ctrl + P

Question 3.
In tux paint scout option is used for ………………
(a) Simple addition
(b) Addition and subtraction to ten
(c) Division
(d) Multiplication
Answer:
(b) Addition and subtraction to ten

Question 4.
Which tool is used to cancel a command given earlier?
(a) Quit
(b) magic
(c) eraser
(d) undo
Answer:
(d) undo

Question 5.
Which tool is like a rubber stamps or stickers?
(a) text
(b) stamp
(c) eraser
(d) magic
Answer:
(b) stamp

II. Fill in the Blanks

1. When Tux paint first loads, a ………………… screen will appear.
2. The ………………… tool helps us to draw freehand drawings.
3. The ………………… tool is used to draw lines.
4. ………………… tool has a set of special tools.
5. Clicking the ………………… button will start a new drawing.

Answer:

1. title / credits
2. paint brush
3. line
4. Magic
5. New

III. Question and answers

Question 1.
What is the use of shapes tool?
Answer:
Shape tool is used to draw some simple filled and un-filled shapes.

Question 2.
What is play Arcade Game?
Answer:
This option is used to select and play one of the four open ended “arcade style” games.

Question 3.
Which tool is used to closed Tux Paint window?
Answer:
Quit tool is used to close Tux Paint window.

Question 4.
What is the use of selector?
Answer:
Selector display the options associated with the specific tool.

Question 5.
What is help area?
Answer:
Help area is in the bottom of the screen. It provides tips and other information while you draw.

Question 6.
What is magic tool?
Answer:
Magic tool is a set of special tools, selecting one of the ‘magic’ effects from the selector situated in the right side. This tool provides countless number of special visual effects if it is used in various combination with other tools.

IV. Give Long answers

Question 1.
What are the short keys in computers?
Answer:

Students can Download Maths Chapter 4 Information Processing Ex 4.3 Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 2 Chapter 4 Information Processing Ex 4.3

Question 1.
Choose the correct answers:

Question (i)
In questions A and B, there are four groups of letters in each set. Three of these sets are like in some way while one is different. Find the one which is different.
A. (a) C R D T (b) A P B Q (c) E U F V (d) G W H X
B. (a) H K N Q (b) I L O R (c) J M P S (d) A D G J
Answer:
A. (a) C R D T (b) A P B Q (c) E U F V (d) G W H X
Hint:
The four groups of letters are
CRDT APBQ EUFV GWHX
The above can be written as

We find that when we take 1st & 3rd letter & 2nd & 4th letter as 2 pairs, the 3rd letter is the next letter alphabetically to the 1st letter.
Similarly the 4th letter is alphabetically the next letter of the 2nd letter.
i.e CD, AB, EF, GH & PQ, UV, WX
Only in CRDT, we have T instead of ‘S’. So,
Answer:
in CRDT ⇒ Option (a)

B. The four groups of letters are
HKNQ ILOR JMPS ADGI
If we notice, we find that 2 letters are missing in the sequence, ie.
H_IJK_LMN_OPQ I_JKL_MNO_PQR
L_KLM_NOP_QRS A_BCD_EFG_HI
We find that only in ADGI, the difference is only one letter between G & I.
Hence it is the odd one out.

Question (ii)
A group of letters are given. A numerical code has been given to each letter. These letters have to be unscrambled into a meaningful word. Find out the code for the word so formed from the 4 answers given.

(a) 2 3 4 1 5 6
(b) 5 6 3 4 2 1
(c) 6 1 3 5 2 4
(d) 4 2 1 3 5 6
Answer:
(b) 5 6 3 4 2 1
hint:
Given code is

Option (a) is 234156. When we substitute number for each letter from code, we get,

Option (b) is 563421, similarly, we get 5 6 3 4 2 1

Option (c) is

Option (d) is

So, only in option b, we get a meaningful word, i.e PENCIL.
Hence, answer is Option (b)

Question (iii)
In questions I and II, there are based on code language. Find the correct answer from the four alternatives given. A
C In a certain code, ‘M E D I C I N E’ is coded as ‘COMPUTER’ written in the same code?
(a) C N P R V U F Q
(b) C M N Q T U D R
(c) R F U V Q N P C
(d) R N V F T U D Q
Answer:
(C) R F U V Q N P C
Hint:
It is given that in a certain code M E D I C I N E is coded as E O J D J E F M When we observe the word & the code, we find that, there is a pattern.

[to understand, see the matching shapes]
To get the code from the word, we follow the below steps
1.
swap 1st & last letters, so we get
E [ E D I C I N ] M
2. For the middle letters, replace the letters with their alphabetically next letters, so we get

3. Now we have to reverse the order of the middle letters in the bracket, so we get
E[O J D J E F]M = E O J D J E F M
Thus we get the code.
So similarly, we have to follow the 3 steps to get code, therefore:
for

Step 1: Swap 1 st & last letters, so we get
R [O M P U T E ]C
Step 2: For the middle letters, replace the letters with alphabetically next letters, so we get
R [P N Q V U F] C
Step 3: Reverse the word of letters in the bracket to we get
R [F U V Q N P] C
∴ Ans is R F U V Q N P C ⇒ Option C

Question (iv)
If the word ‘PHONE’ is coded as ‘S K R Q H’, how will ‘R A D I O’ be coded?
(a) S C G N H
(b) V R G N G
(c) U D G L R
(d) S D H K Q
Answer:
(C) U D G L R
hint:
If PHONE is coded as S K R Q H
Find that code for R A D I O

We find that we get the code, by 3rd letter alphabetically so, from P, skipping Q & R, we get S.
Similarly, from H, skipping I & J, we get K
Like wise for R A D I O, skipping the 2 alphabets
From R, skip S & T → U
From A, skip B & C → D

From D skip E & F → G
From I skip J & K → L
From O skip P & Q → R
Answer:
is U D G L R ⇒ Option c

Question 2.
Fill in the blanks (Use Atbash Cipher that is given in code 3)
For this question, we need to use Atbash cipher. For Atbash cipher, first we write the alphabets from A to Z and then in reverse from Z to A below that.
ABCDEFGHIJKLMNOPQRSTUVWXYZ
ZYXWVUTSRQPONMLKJIHGFEDCBA

Question (i)
G Z N R O = …………
Answer:
TAMIL
Hint:
Now to solve, we look up the corresponding letter from the table to replace in code to get the actual word.
So, for G Z N R O, from table,
for G, it is T
for Z, It is A
for N, it is M
for R, it is I
for O, it is L
So , the actual word is TAMIL

Question (ii)
V M T O R H S = ………
Answer:
ENGLISH
Hint:
V M T O R H S
To solve, we look up the corresponding letter from table to replace in code to get the actual word.
For V, it is E
for M, it is N
for T, it is G
for O, it is L
for R, it is I
for H, it is S
for S, it is H
Therefore we get E N G L I S H = ENGLISH

Question (iii)
N Z G S V N Z G R X H = ………
Answer:
MATHEMATICS
Hint:
Similarly as above for

Question (v)
H X R V M X V = ………..
Answer:
SCIENCE
Hint:

Question (v)
HLXRZO HXRVMX V = ………..
Answer:
SOCIAL SCIENCE
Hint:

Question 3.
Match the following (a = 00 ……… Z = 25)

Answer:
(i) – c
(ii) – d
(iii) – a
(iv) – e
(v) – b
Solution:
Given that the code is

Hint:
(i) Mathematics is

So matching option is c

(ii) addition is

Matching option is d

(iii) Subtraction is

Matching option is a

(iv) multiplication is

Matching option is e, however instead of 25, it should be 08.

(v) division is

Matching option is b

Question 4.
Frame Additive cipher table (key = 4).
Solution:
Step 1 : write all alphabets
Step 2 : Assign numbers to each alphabet starting from 00 till 25.
Step 3 : add key value (here it is 4) to the numbers assigned in step 2 to form cipher table

Question 5.
A message like “Good Morning” written in reverse would instead be “Doog Gninrom”. In the same way decode the sentence given below: “Ot dnatsrednu taht scitamehtam nac eb decneirepxe erehwreve ni erutan dna laer efil.”
Solution:
Given that good morning written in reverse is doog gninrom.
We have to decode the below by reversing, so,
Ot dnatsrednu taht scitamehtam nac eb decneirepxe erehwreve ni erutan dna laer efil.
Answer:
to understand that mathematics can be experienced everywhere in nature and real life.

Question 6.
Decode the given Pigpen Cipher text and compare your answer to get the Activity 3 result.

(i) The room number in which the treasure took place

(ii) Place of the treasure

(iii) The name of the treasure

Solution:
(i) The room in which the treasure took place = 28
(ii) The place of treasure = Chair
(iii) Identity of treasure = Gift voucher.

Students can Download Maths Chapter 4 Information Processing Additional Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 2 Chapter 4 Information Processing Additional Questions

Question 1.
Find HCF of 52 and 78 using repeated division.
Solution:

26 is the HCF of 52 & 78

Question 2.
Find HCF of 56 & 98 using repeated subtraction method.
Solution:
Let m = 98, n = 56
m – n = 98 – 56 = 42 ; now m = 56 & n = 42
m – n = 56 – 42 = 14 ; now m = 42 & n = 14
m – n = 42 – 14 = 28 ; now m = 14 & n = 28
m – n = 28 – 14 = 14 ; now = 14 & n = 14
∴ HCF of 98 & 56 is 14.

Question 3.
Find the first 10 terms of the Fibonacci series.
Solution:
Let us first write down the first 2 terms which are 1, 1. To find the remaining terms, we use the general formula. F(n) = F(n – 1) + F(n – 2)
∴ F(3) = F(2) + F(1)
F(1) = 1; F(2) = 1
F(3) = 1 + 1=2
F(4) = F(3) + F(2) = 2 + 1 = 3
F(5) = F(4) + F(3) = 2 + 3 = 5
∴ The first 10 terms are; 1, 1, 2, 3, 5, 8,13, 21, 34, 55

Question 4.
In a particular method of decoding, the word SECRET is written as TFDSFU. What is the cipher text for PASSWORD?
Solution:
Given that SECRET is written as TFDSFU. We notice that every letter is substituted by the next letter alphabetically.
So S is substituted by T
E by F, C by D, R by S E by F, & T by U
∴ for

similarly we have to substitute
∴ The cypher is QBTTXPSE.

Question 5.
Using the Pigpen code, decode the below message

Solution:
The pigpen code is generated by

By taking the outlines corresponding to each letter, we get

∴ The message is THANK YOU

Question 6.
Using the reflection table given below, find the encoded message Reflection table.

Message: PBATENGHYNGVBAF
Solution:
To decode the above message, let us substitute the letters that correspond’to the message from the reflection table. So, we get
P → C
B → O
A → N
T → G
E → R
N → A
G → T
H → U
Y → L
N → A
G → T
V → l
B → O
A → N
F → S
The word is CONGRATULATIONS!

Students can Download Maths Chapter 4 Information Processing Intext Questions and Answers, Notes Pdf, Samacheer Kalvi 8th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.

Tamilnadu Samacheer Kalvi 8th Maths Solutions Term 2 Chapter 4 Information Processing Intext Questions

Exercise 4.1
Activity 1. (Text book Page no. 83)

Question 1.
Draw a Golden Spiral using Fibonacci squares.

Answer:

Activity – 2 (Text book Page no. 85)

Question 1.
Using the given Table I, find the pattern, Answer the following questions and colour the values in the given Table II. One is done for you.
Table I

1. Where are the even Fibonacci Numbers?
Colour both the term n and where F(n) is even in
Do you find any pattern?
Every Third Fibonacci number is a multiple of 2(even).
i.e. a multiple of F(3) or 2 = F(3).

2. Where there are Fibonacci numbers which are multiple of 3?
Colour both the term n and where F(n) is multiple of 3 in red.
Write down the pattern you find
Every 4th Fibonacci number is a multiple of 3.
i.e. a multiple of F(4) or 3 = F(4).

3. What about the multiple of 5?
Colour both the term n and where F(n) is multiple of 5 in 1
Write down the pattern you find.
Every 5th Fibonacci number is a multiple of F(5) or 5 = F(5)
i.e. a multiple of F(4) or 3 = F(4)

4. What about the multiple of 8?
Colour both the term n where F(n) is multiple of 8 in green.
Write down the pattern you find.
Every 6th Fibonacci number i.e. a multiple of F(6) or 8 = F(6)

Table II

Solution:

R – Red
Y – Yellow
B – Blue
G – Green

Exercise 4.3
Try This (Text book Page no. 94)

Question 1.
Convert cipher code written in the school panel board as given in figure below.

Solution:
Cipher code given.
EAPLKEAPUSG UG NWP AJWYP NYEJKXG KOYAPUWNG, SWEFYPAPUWNG WX AVCWXUPLEG; UP UG AJWYP YNBKXGPANBUNC – QUVVAE FAYV PLYXGPWN
Mathematics is not about numbers, equations, computations or algorithms, it is about understanding. – William Paul Thurston

Activity 3. (Text book Page No. 95)

Code 1: Pigpen

Question 1.
Fill in the blank boxes and decode

The Pigpen code looks like meaningless writing, but it is quite easy to catch on to. Each letter is represented by the part of the “Pigpen” that surrounds it.

The first code uses the following key. To complete the code, you need to work out how to use the key to decode the message.

Solution:

To decode

Try These (Text book Page no. 97)

Question 1.
Use Pigpen Cipher code and write the code for your name ………. chapter names

(i) LIFE MATHEMATICS
(ii) ALGEBRA
(iii) GEOMETRY
(iv) INFORMATION PROCESSING

Solution:
For Pigpen, we should first construct the Criss Cross pattern & then fill with alphabets.
Step 1:

Step 2:
Fill the above with all the alphabets from A to Z.

Step 3:
So, the secret code is got by the outline of each letter in the above patterns. So for

Similarly for all the others. Therefore Pigpen code is

Hence if your name is RAM, the corresponding pattern is

Let us now write the given words with Pigpen code.

Question 2.
Decode the following Shifting and Substituting secret codes given below. Which one is a easier for you?

Solution:
Decode using shifting method. Let us shift & see by trial & error method.
Let us substitute ‘b’ for ‘a’, V for ‘b’ & so on.

Message: M N S G H M F H R H L O N R R H A K D
Decoded text: NOTHING IS IMPOSSIBLE
Decode using substituting method:

We find that Pigpen code has been used, by substituting for the symbols from the table that we constructed earlier, we go the message.
NOTHING IS IMPOSSIBLE