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The change in one quantity leads to change in another quantity will see in the following situations.

1. If speed increases then time decreases. 

2. In a family, the number of persons are increased then their consumption will also increases. 

3. If water consumption increases then water levels decreases. 

4. If the capacity of worker’s increases then time decreases. 

5. If thickness of a wire increases then its resistance decreases.

1. The relation between number of students to number of teachers. 

2. Number of buffaloes to their consumption of grass. 

3. Number of workers to length of wall.

False

If x and y are in inverse proportion, then xy = k (constant) e.g. Let x= 2 and y = 3

xy = 2 x 3= 6. Now, x + 1=2 + 1 = 3 and y+ 1 = 3 + 1 = 4

Then, (x + 1)(y+1) = 3 x 4 = 12 [not in inverse proportion]

Hence, (x+ 1)and (y + 1) cannot be in inverse proportion.

Answer is The surface waves

Class 8 Maths MCQ Questions of Playing with Numbers with Answer whenever practiced appropriately can assist you with getting best score in exams. Below you will discover MCQ Questions of Playing with Numbers Class 8 Maths that will help you in scoring great marks in the assessments. These MCQ Questions for class 8 with answers will increase your abilities and comprehend ideas in a superior way.

Students are encouraged to practice the MCQ Questions for class 8 with Answers is over here. These MCQ Questions are set up according to the latest Exam Pattern. The multiple-choice questions of all chapters are given at Sarthaks eConnect, for all understudies to get familiar with the ideas and concepts completely and score better checks in exams. Additionally, learn significant MCQ Questions for class 8 Maths here. 

Practice MCQ Question for Class 8 Maths chapter-wise

1. The generalised form of the number 52 is

(a) 10 × 5 + 2
(b) 100 × 5 + 2
(c) 10 × 2 + 5
(d) 10 × 5

2. The generalised form of the number 39 is

(a) 10 × 3 + 9
(b) 100 × 5 + 2
(c) 10 × 2 + 9
(d) 10 × 5

3. Write the number whose expanded form is as given: 3×100+3×10+3.

(a) 303
(b) 333
(c) 330
(d) 300

4. Write the number whose expanded form is as given: 100 x 7 + 10 x 1 + 8.

(a) 718
(b) 700
(c) 720
(d) 300

5. Which of the following numbers is divisible by 2?

(a) 19
(b) 27
(c) 99
(d) 50

6. Which of the following numbers is divisible by 2?

(a) 179
(b) 235
(c) 500
(d) 673

7. Which of the following numbers is not divisible by 2?

(a) 54
(b) 37
(c) 60
(d) 98

8. If the number 1 x 8 is divisible by 3, then x is equal to

(a) 0 or 3 or 6 or 9
(b) 4
(c) 5
(d) 7

9. If the number 9y7 is a multiple of 3, then y =

(a) 4
(b) 3
(c) 6
(d) 2 or 5 or 8

10. If 21y5 is a multiple of 9, where y is a digit, what is the value of y?

(a) 1
(b) 2
(c) 3
(d) 2 or 5 or 8

11. Which of the following numbers is not divisible by 3?

(a) 234
(b) 243
(c) 324
(d) 457

12. Which of the following numbers is divisible by 3?

(a) 145
(b) 237
(c) 709
(d) 400

13. Which of the following numbers is divisible by 9?

(a) 234
(b) 334
(c) 444
(d) 434

14. Which of the following numbers are not divisible by 5?

(a) 20
(b) 125
(c) 122
(d) 200

15. Which of the following numbers are divisible by 10?

(a) 99
(b) 45
(c) 110
(d) 75

16. If a three-digit number 24x is divisible by 9, then find out the value of x, where x is a digit.

(a) 4
(b) 3
(c) 5
(d) 7

17. The number 2146587 is divisible by:

(a) 7
(b) 3
(c) 11
(d) None of the above

18. Which value is divisible by 5?

(a) 36
(b) 90
(c) 26
(d) 81

19. If the three-digit number 80x is divisible by 9, what is the value of x?

(a) 1
(b) 9
(c) 7
(d) 4

20. If N divided by 5 leaves a remainder of 3, then one's digit of N must be ______

(a) Either 3 or 6
(b) Either 3 or 8
(c) Either 8 or 1
(d) Either 8 or 6

21. Which of the following number is divisible by 12?

(a) 123452
(b) 79968
(c) 78968
(d) 79998

22. The number  477  is divisible by each of the following numbers except

(a) 3
(b) 9
(c) 6
(d) None of these

23. If the division N+5 leaves a remainder of 3, what might be the one's digit of N?

(a) 2
(b) 3
(c) 4
(d) 5

24. If a number is divisible by 8, it must be divisible by 4. Is it true or false

(a) True
(b) False
(c) Nothing to say
(d) Cannot predict

25. Which one of the following is not a prime number?

(a) 31
(b) 61
(c) 71
(d) 91

Answer:

1. Answer: (a) 10 × 5 + 2

Explanation: 52 = 50+2

=(10×5)+(2×1)

=10×5+2

2. Answer: (a) 10 × 3 + 9

Explanation: 39 = 30+9

=(10×3)+(9×1)

=10×3+9

3. Answer: (b) 333

Explanation: The general form of any three-digit number is, abc =a×100+b×10+c

Here, 3×100+3×10+3

=300+30+3

=333

4. Answer: (a) 718

Explanation:100 x 7 + 10 x 1 + 8

= 700 + 10 + 8

= 718

5. Answer: (d) 50

Explanation: In 19, 27, 99, one’s digit is not divisible by 2.

6. Answer: (c) 500

Explanation: In 500, one’s digit is divisible by 2.

7. Answer: (b) 37

Explanation: In 37, one’s digit is not divisible by 2.

8. Answer: (a) 0 or 3 or 6 or 9

Explanation: 1 + 0 + 8 = 9

1 + 3 + 8 = 12;

9, 12, 15, 18 each is divisible by 3

9. Answer: (b) 3

Explanation: 9 + 2 + 7 = 18

9 + 5 + 7 = 21;

9 + 8 + 7 = 24.

each of 18, 21 and 24 is divisible by 3

10. Answer: (a) 1

Explanation: Since the number 21y5 is a multiple of 9.

So, the sum of its digits 2+1+y+5=8+y is a multiple of 9.

∴(8+y) is either 0 or 9 or 18 or ...

Since y is a digit, so (8+y) must be equal to 9.

i.e., 8+y=9

⇒ y=9−8

=1

11. Answer: (d) 457

Explanation: 4 + 5 + 7 = 16 is not divisible by 3.

12. Answer: (b) 237

Explanation: 2 + 3 + 7 = 12 is divisible by 3.

13. Answer: (a) 234

Explanation: 2 + 3 + 4 = 9 is divisible by 9.

14. Answer: (c) 122

Explanation: To be completely divisible by 5, the number should have 0 or 5 at its one’s digit place.

15. Answer: (c) 110

Explanation: If any number has 0 at its one’s digit place, then it is divisible by 10.

Hence, 110/10 = 11

16. Answer: (b) 3

Explanation: A number is divisible by 9 if the sum of the digits of the number is divisible by 9.

Sum of digits of given number =2+4+x

= 6+x

Let us say that (x+6) is a multiple of 9,

⟹ x + 6 = 9

x=3

17. Answer: (b) 3

Explanation: 2146587 = 2 + 1 + 4 + 6 + 5 + 8 + 7 = 33

Since 33 is divisible by 3, hence 2146587 is divisible by 3

18. Answer: (b) 90

Explanation: At the unit place of 90 we have 0. Hence, as per the divisibility rule for 5, 90 is divisible by 5.

19. Answer: (a) 1

Explanation: Given, 80x is divisible by 9.

Thus, sum of digits of 80x will also be divisible by 9.

8 + 0 + x is divisible by 9 only if, x = 1

8 + 0 + 1 

= 9

20. Answer: (b) Either 3 or 8

Explanation: N divided by 5 leaves a remainder of 3

→ We know, A number divisible by 5 has Unit Digit 0 or 5.

⇒ Unit Digit of N=0+3=3 or 5+3=8

21. Answer: (b) 79968

Explanation: Divisibility rule of 12: Number divisible by both 3 and 4.

⇒  Divisibility rule of 3: A number is divisible by 3 if the sum of the digits is divisible by 3.

⇒  Divisibility rule of 4: A number is divisible by 4 if the last two digits are a multiple of 4.

⇒  123452=1+2+3+4+5+2=17

⇒  78968=7+8+9+6+8=28

⇒  123452 and 78968 are not divisible by 3 so it's not divisible by 12

⇒  79998=7+9+9+9+8=42, it is divisible by 3.

⇒  Last two digits 98 is not divisible by 4

∴   79998 is not divisible by 12.

⇒   79968=7+9+9+6+8=39, it is divisible by 3

⇒   Last two digits 68 are divisible by 4.

∴   79968 is divisible by 12.

22. Answer: (c) 6

Explanation: Factors of 477=1,3,9,53,159,477

The number 477 is divisible by each of the following numbers except 6.

23. Answer: (b) 3

Explanation: If N/5 gives remainder 3, then N = 5a+3 for a natural number a.For a being even, 5a has unit place 0 and 3 added gives unit place 3 For a being odd, 5a has unit place 5 and 3 added gives unit place 8. So, it's either 3 or 8.

24. Answer: (a) True

Explanation: A number divisible by 8 will be divisible by 4 as 4 is a factor of 8 (Example: 24 is divisible by both 4 and 8),  but vice versa may not be true (Example: 20 is divisible by 4 but not by 8). So, the answer is True.

25. Answer: (d) 91

Explanation: 91 is divisible by 7 and 13. So, it is not a prime number.
Rest all the given numbers are prime numbers since they don't have any factors other than 1 and themselves.

Click here Practice MCQ Question for Playing with Numbers Class 8

i) Time – work capacity 

ii) Speed – distance 

iii) Time – speed

Correct option is (D) All the above

(A) If speed increases then required time decreased.

\(\therefore\) It is an example of inverse proportion.

(B) If ability to work is increases then taken time to complete the work is decreases.

\(\therefore\) It is an example of inverse proportion.

(C) If population of a country increases then the area of land per person decreases.

\(\therefore\) It is an example of inverse proportion.

D) All the above

Rocks in the deeper interior of the earth undergo displacement and faults due to plate movements and other causes. Under such situations, severe pressure is exerted on the earth’s lithosphere and seismic waves are generated just like waves in a pond spreading, in all directions when a heavy object falls into it. These waves create tremors on the earth’s surface. These tremors are experienced by us as an earthquake.

The deep points inside the earth where the earth-quake occurs are known as focus and the point vertically above it on the earth’s surface is known as epicenter.

A – shows the epicenter B – shows the focus

The features of earthquakes having different intensities

The plate margins are active with volcanoes. The hot molten rock that comes out through the fissures on the crust. Volcanoes are formed by such molten rock material coming out through the fissures along the plate margins.

• Earthquakes
• Volcanic eruption

• Volcanic eruptions
• Earthquakes

Fold mountains are formed along the convergent margins. The Himalayas, the Alps, the Andes, the Atlas, etc are all folded mountains. The Himalaya fold mountain is formed between the Indian Plate and the Eurasian plate.

Both are democracies. Yet, they dealt with the question of power sharing differently. In Belgium, the leaders have realised that the unity of the country is possible only by respecting the feelings and interests of different communities and regions. Such a realisation resulted in mutually acceptable arrangements for sharing power. Sri Lanka shows us a contrasting example. It shows us that if a majority community wants to force its dominance over others and refuses to share power, it can undermine the unity of the country and force the country back several hundred years with internal conflicts and civil wars.

(a) Convergent margins. Fold mountains are formed along the convergent margins, eg. Himalaya.

(b) Divergent margins: Magma comes out through the gap formed due to the divergence of plates and solidifies to form mountains.

Eg. Mid Atlantic Ridge.

The average thickness of the lithosphere is 100 kilometers.

Due to enhancing density and pressure the temperature goes on increasing gradually towards inside of the interior of the earth.

The high pressure in the interior core keeps this layer firm and solid in some parts, in spite of the temperature as high as 5000°C.

Geology is the science dealing with the origin and types of rocks found in the interior of the earth.

The actual shape of the Earth is spherical. The curvature of the Earth is small as compared to its big size. For a small area upto 100 sq. miles, this curvature is negligible. Therefore, it appears flat.

The Mantle or Mesosphere is located between 2850 – 2900 km beneath the earth crust.

The density of continents is lesser than the layer supporting the ocean beds, so the continents came floating upwards at the time of the formation and solidification of the earth, as the lighter things come upwards floating over the heavier things i. e. Sial is lighter than Sima

Information about forces operating inside the earth is taken by the study of seismic waves, materials thrown up by volcanoes and the evidence from the theories of the origin of the earth.

If the Earth were flat, the whole world would have the sunrise and sunset at the same time. As the Earth is spherical and rotates from West to East, places in the East see the Sun earlier than the places in the West.

Two types of movements are due to isostasy and tectonic plates. Isostasy is the process of natural balance between different landforms and the sliding movement of the tectonic plates of the earth’s crust.

The three layers of earth’s interior are: 

1. Core 

2. Mantle 

3. Crust

NIFE is found in the inner core of die earth. NIFE is composed of Nickel (Ni) and Iron (Fe), being heavy metals and having high density, these are found deep inside the earth.

The crust is called Lithosphere made of solid rocks with a thickness of 60 km. below high mountains and 6-12 km below the oceans.

The solid state of the inner core is due to high density and pressure which have compressed molten rock material and keep this layer firm and solid in some parts due to high pressure inspite of the temperature of 5000°C.

The crust is made of solid rocks and divided into oceans and continents.

(a) Sial is the upper layer or crust of the earth. The name Sial is based on the excess of Silica and Aluminium. The depth of Sial is 60 km. 

(b) Sima is the second layer of earth which gives support to the ocean beds. There is the excess of Silica and Magnesium. 

(c) ‘Nife’ means Nickel (Ni) and Iron (Fe) due to the majority of Nickel and Iron in the core, 

(d) Core of earth is responsible for earth’s magnetic field because it is composed of iron and nickel which is responsible for earth’s magnetism. Magnetic field is oriented towards North and South Poles. 

(e) Several drastic changes may occur during the earthquake. It depends on the intensity of the earthquake. If intensity is 8 or more buildings may break up, casualties and major changes on the landforms as broad breaking gaps, origin or disappearing of several small islands.

Due to the extreme temperature of 2200° C, every matter is in liquid and gaseous state in the interior core, the temperature in the mantle ranges from 870° C to 2200° C, so things are in semi – liquid to liquid state, the crust, a layer of 60 km, breadth, is made of solid rocks with a density of 2 – 3, g/Cm3. The density goes on increasing to 3-4g/Cm3 in the mantle and 10-13 g/Cm3 in the core.

Crust : 

(a) Depth 35-50 km below continents and 6-12 km. below the oceans. 

(b) Temperature — Less than 870°C 

(c) Density — 2.7 g/Cm3 – 5.5 g/Cm3. 

Mantle : 

(a) Depth — 50 – 2900 km. 

(b) Temperature — 1500° C – 2200°C 

(c) Density — 3 g/Cm3 – 4.5 g/Cm3 

Core : 

(a) Depth — 2900 km – 3500 km 

(b) Temperature — 2200°C – 5000°C 

(c) Density — 10.0 g/Cm3 – 13.6 g/Cm

The transitional zone between crust and mantle is Moho Discontinuity which is the dividing zone between solid and semi-solid state of rocks due to the increasing temperature as the depth increases. The boundary between mantle and core is known as Gutenberg Discontinuity, below this zone both density and temperature going on increasing. The density is more than 13 and temperature is more than 2200°C.

The interior of the earth is divided into three major parts i.e. crust, mantle and core. The crust consists of majority of, silica and aluminium and is called ‘SIAL’, mantle is called SIMA due to the majority of silica and magnesium and is called SIMA, which makes the bed of oceans and the core is called NIFE with excess of Nickel and Iron (Ni + Fe).

Mantle lies between 60 – 2900 km. depth. It is divided into two parts namely upper mantle and lower mantle, which are in the form of solid rocks and semi-molten rocks respectively.

Moho Discontinuity is the boundary between crust and mantle and Gutenberg Discontinuity is the boundary between mantle and core.

The Earth has a spherical snape. Along its curved surface, the appearance of a ship is gradual. We see first the smoke, then the mast and then the hull. If the Earth were flat, the entire ship would be seen all at once.

The Earth is not a perfect sphere. It is slightly flattened at both the poles. It is due to the centripetal force produced by the rotation of the Earth.

At the depth of 100 – 250 km. The mantle is partially molten and known as asthenosphere, with a temperature of 1100°C.

At the time of the origin of the earth every planet and meteorites were floating in the space and the materials of the earth were same as that of the meteorites. So, the scientists can calculate the composition of rocks ofthe earth by studying the materials found in the meteorites.

At the depth of 100 – 250 km the mantle is partially molten and known as asthenosphere due to the temperature around 1100°C along with greater pressure and density.

Rosie was the name of the first transgenic cow. Gene for human alpha lactalbumin was introduced in its gene, which made the milk nutritionally richer.

Correct Answer is: (A) Lysozyme 

Lysozyme or Muramidase or Glycoside hydrolase is the enzyme discovered by Alexander Fleming is responsible for breaking down bacterial cell wall. 

Correct Answer is: (D) All of these

The gynoecium (whether composed of a single carpel or multiple "fused" carpel’s) is typically made up of an ovary, style, and stigma as in the center of the flower.

Gene therapy

Correct option is (A) (-5)^-7

\((-5)^{-3}\times(-5)^{-4}=(-5)^{(-3)+(-4)}\)

= \((-5)^{-7}\)

Correct option is  A) (-5)^-7