MCQs of Maths for Class 8

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class 8

Here are MCQs of Maths for Class 8 with answers:

MCQs for class 8

1. The perimeter of a rectangle is 30 cm. If the length is 10 cm, what is the width?

  • A) 5 cm
  • B) 7 cm
  • C) 6 cm
  • D) 4 cm

Answer: A) 5 cm
The perimeter of a rectangle is given by 2(l+w)2(l + w)2(l+w). Here, 2(10+w)=302(10 + w) = 302(10+w)=30, so w=5w = 5w=5 cm.

2. The area of a triangle is 24 cm², and the base is 8 cm. What is the height?

  • A) 4 cm
  • B) 6 cm
  • C) 8 cm
  • D) 3 cm

Answer: B) 6 cm
The area of a triangle is 12×base×height\frac{1}{2} \times \text{base} \times \text{height}21​×base×height. Using Area=24\text{Area} = 24Area=24 and base=8\text{base} = 8base=8, we get 24=12×8×h24 = \frac{1}{2} \times 8 \times h24=21​×8×h, so h=6h = 6h=6 cm.

3. If the sum of two consecutive integers is 43, then the integers are:

  • A) 21 and 22
  • B) 20 and 23
  • C) 21 and 23
  • D) 22 and 21

Answer: A) 21 and 22
Let the two consecutive integers be xxx and x+1x+1x+1. Then x+(x+1)=43x + (x+1) = 43x+(x+1)=43. Solving, 2x+1=432x + 1 = 432x+1=43, so x=21x = 21x=21. Therefore, the integers are 21 and 22.

4. The value of 333^333 is:

  • A) 27
  • B) 9
  • C) 81
  • D) 36

Answer: A) 27
33=3×3×3=273^3 = 3 \times 3 \times 3 = 2733=3×3×3=27.

5. The ratio of the circumference to the diameter of a circle is:

  • A) 3
  • B) π\piπ
  • C) 2
  • D) 4

Answer: B) π\piπ
The ratio of the circumference to the diameter of a circle is always π\piπ.

6. The value of xxx in the equation 2x−3=72x – 3 = 72x−3=7 is:

  • A) 2
  • B) 5
  • C) 7
  • D) 4

Answer: B) 5
Solving 2x−3=72x – 3 = 72x−3=7, we get 2x=102x = 102x=10, so x=5x = 5x=5.

7. If the angles of a triangle are in the ratio 2:3:5, then the largest angle is:

  • A) 90°
  • B) 100°
  • C) 120°
  • D) 140°

Answer: C) 120°
The sum of the angles in a triangle is 180°. Let the angles be 2x,3x,5x2x, 3x, 5x2x,3x,5x. So, 2x+3x+5x=180°2x + 3x + 5x = 180°2x+3x+5x=180°, solving for xxx, we get x=15x = 15x=15. The largest angle is 5x=75°5x = 75°5x=75°.

8. The area of a square is 64 cm². What is the length of its side?

  • A) 8 cm
  • B) 6 cm
  • C) 7 cm
  • D) 4 cm

Answer: A) 8 cm
The area of a square is side2\text{side}^2side2. So, side2=64\text{side}^2 = 64side2=64, thus the side is 64=8\sqrt{64} = 864​=8 cm.

9. The simple interest on a sum of Rs 5000 at 5% per annum for 2 years is:

  • A) Rs 400
  • B) Rs 500
  • C) Rs 600
  • D) Rs 700

Answer: A) Rs 500
Simple Interest SI=P×R×T100SI = \frac{P \times R \times T}{100}SI=100P×R×T​. Here, P=5000P = 5000P=5000, R=5R = 5R=5, and T=2T = 2T=2. Thus, SI=5000×5×2100=500SI = \frac{5000 \times 5 \times 2}{100} = 500SI=1005000×5×2​=500 Rs.

10. The product of 3 consecutive integers is 210. The integers are:

  • A) 5, 6, 7
  • B) 6, 7, 8
  • C) 7, 8, 9
  • D) 8, 9, 10

Answer: A) 5, 6, 7
The product of 5, 6, and 7 is 5×6×7=2105 \times 6 \times 7 = 2105×6×7=210.

11. A right circular cylinder has a radius of 4 cm and a height of 9 cm. The volume is:

  • A) 36π36\pi36π cm³
  • B) 144π144\pi144π cm³
  • C) 363636 cm³
  • D) 144144144 cm³

Answer: A) 36π36\pi36π cm³
The volume of a cylinder is πr2h\pi r^2 hπr2h. Substituting r=4r = 4r=4 and h=9h = 9h=9, we get π×42×9=36π\pi \times 4^2 \times 9 = 36\piπ×42×9=36π cm³.

12. The number of sides of a regular polygon, if each interior angle is 108°, is:

  • A) 6
  • B) 7
  • C) 8
  • D) 5

Answer: D) 5
The formula for the interior angle of a regular polygon is (n−2)×180°n\frac{(n-2) \times 180°}{n}n(n−2)×180°​. Setting this equal to 108°, we get n=5n = 5n=5.

13. The HCF of 36 and 60 is:

  • A) 6
  • B) 12
  • C) 18
  • D) 24

Answer: B) 12
The HCF of 36 and 60 is the largest number that divides both. Using prime factorization, we get HCF=12\text{HCF} = 12HCF=12.

14. If a=4a = 4a=4 and b=3b = 3b=3, then the value of a2+b2a^2 + b^2a2+b2 is:

  • A) 16
  • B) 25
  • C) 7
  • D) 10

Answer: B) 25
a2+b2=42+32=16+9=25a^2 + b^2 = 4^2 + 3^2 = 16 + 9 = 25a2+b2=42+32=16+9=25.

15. The sum of the first 10 odd numbers is:

  • A) 55
  • B) 100
  • C) 60
  • D) 50

Answer: A) 55
The sum of the first nnn odd numbers is given by n2n^2n2. For n=10n = 10n=10, the sum is 102=10010^2 = 100102=100.

16. The value of (x+3)(x+4)(x + 3)(x + 4)(x+3)(x+4) is:

  • A) x2+7x+12x^2 + 7x + 12×2+7x+12
  • B) x2+7x+10x^2 + 7x + 10×2+7x+10
  • C) x2+5x+12x^2 + 5x + 12×2+5x+12
  • D) x2+6x+12x^2 + 6x + 12×2+6x+12

Answer: A) x2+7x+12x^2 + 7x + 12×2+7x+12
Expanding (x+3)(x+4)=x2+4x+3x+12=x2+7x+12(x + 3)(x + 4) = x^2 + 4x + 3x + 12 = x^2 + 7x + 12(x+3)(x+4)=x2+4x+3x+12=x2+7x+12.

17. The LCM of 12 and 18 is:

  • A) 36
  • B) 24
  • C) 54
  • D) 48

Answer: A) 36
The LCM of 12 and 18 is the smallest multiple that is divisible by both. The LCM is 36.

18. The surface area of a cube with a side of 6 cm is:

  • A) 72 cm²
  • B) 108 cm²
  • C) 96 cm²
  • D) 84 cm²

Answer: B) 108 cm²
The surface area of a cube is 6×side26 \times \text{side}^26×side2. Substituting side=6\text{side} = 6side=6, we get 6×62=6×36=1086 \times 6^2 = 6 \times 36 = 1086×62=6×36=108 cm².

19. The sum of angles of a quadrilateral is:

  • A) 180°
  • B) 360°
  • C) 90°
  • D) 270°

Answer: B) 360°
The sum of the interior angles of a quadrilateral is always 360°.

20. The value of 5x+2=3x+85x + 2 = 3x + 85x+2=3x+8 is:

  • A) 3
  • B) 2
  • C) 4
  • D) 5

Answer: C) 4
Solving 5x+2=3x+85x + 2 = 3x + 85x+2=3x+8, we get 2x=62x = 62x=6, so x=4x = 4x=4.

21. The value of (3x+5)−(2x−7)(3x + 5) – (2x – 7)(3x+5)−(2x−7) is:

  • A) x+12x + 12x+12
  • B) x+2x + 2x+2
  • C) x−2x – 2x−2
  • D) 5x+125x + 125x+12

Answer: A) x+12x + 12x+12
Simplifying (3x+5)−(2x−7)=3x+5−2x+7=x+12(3x + 5) – (2x – 7) = 3x + 5 – 2x + 7 = x + 12(3x+5)−(2x−7)=3x+5−2x+7=x+12.

22. The area of a circle with a radius of 7 cm is:

  • A) 49π49\pi49π cm²
  • B) 14π14\pi14π cm²
  • C) 7π7\pi7π cm²
  • D) 494949 cm²

Answer: A) 49π49\pi49π cm²
The area of a circle is πr2\pi r^2πr2. For r=7r = 7r=7, the area is π×72=49π\pi \times 7^2 = 49\piπ×72=49π cm².

23. If a coin is tossed 3 times, what is the probability of getting exactly 2 heads?

  • A) 38\frac{3}{8}83​
  • B) 18\frac{1}{8}81​
  • C) 14\frac{1}{4}41​
  • D) 12\frac{1}{2}21​

Answer: A) 38\frac{3}{8}83​
The total possible outcomes are 23=82^3 = 823=8. The favorable outcomes for exactly 2 heads are HHT, HTH, and THH. Thus, the probability is 38\frac{3}{8}83​.

24. The ratio of the areas of two squares is 1:4. What is the ratio of their sides?

  • A) 1:2
  • B) 1:4
  • C) 2:1
  • D) 4:1

Answer: A) 1:2
The area of a square is proportional to the square of its side. So, if the area ratio is 1:4, the ratio of the sides is 1:21:21:2.

25. The volume of a cube with side length 3 cm is:

  • A) 9 cm³
  • B) 27 cm³
  • C) 6 cm³
  • D) 12 cm³

Answer: B) 27 cm³
The volume of a cube is given by side3\text{side}^3side3. For side = 3 cm, the volume is 33=273^3 = 2733=27 cm³.

26. The sum of the interior angles of a pentagon is:

  • A) 180°
  • B) 360°
  • C) 540°
  • D) 720°

Answer: C) 540°
The sum of the interior angles of a polygon is (n−2)×180°(n-2) \times 180°(n−2)×180°. For a pentagon, (5−2)×180°=540°(5-2) \times 180° = 540°(5−2)×180°=540°.

27. What is the value of 535^353?

  • A) 25
  • B) 125
  • C) 75
  • D) 105

Answer: B) 125
53=5×5×5=1255^3 = 5 \times 5 \times 5 = 12553=5×5×5=125.

28. The perimeter of a regular hexagon with a side length of 5 cm is:

  • A) 30 cm
  • B) 20 cm
  • C) 25 cm
  • D) 15 cm

Answer: A) 30 cm
The perimeter of a regular hexagon is 6×side6 \times \text{side}6×side. So, 6×5=306 \times 5 = 306×5=30 cm.

29. The probability of rolling a number greater than 3 on a fair die is:

  • A) 13\frac{1}{3}31​
  • B) 23\frac{2}{3}32​
  • C) 12\frac{1}{2}21​
  • D) 16\frac{1}{6}61​

Answer: B) 23\frac{2}{3}32​
The favorable outcomes are 4, 5, and 6. So, the probability is 36=12\frac{3}{6} = \frac{1}{2}63​=21​.

30. A right-angle triangle has legs of lengths 6 cm and 8 cm. What is the length of the hypotenuse?

  • A) 10 cm
  • B) 12 cm
  • C) 14 cm
  • D) 15 cm

Answer: A) 10 cm
Using Pythagoras’ theorem, c2=a2+b2c^2 = a^2 + b^2c2=a2+b2. Here, c2=62+82=36+64=100c^2 = 6^2 + 8^2 = 36 + 64 = 100c2=62+82=36+64=100, so c=100=10c = \sqrt{100} = 10c=100​=10 cm.

31. What is the value of 7x−2=5x+47x – 2 = 5x + 47x−2=5x+4?

  • A) 2
  • B) 1
  • C) 3
  • D) 4

Answer: B) 1
Solving 7x−2=5x+47x – 2 = 5x + 47x−2=5x+4, we get 2x=62x = 62x=6, so x=3x = 3x=3.

32. The length of a diagonal of a square with side length 5 cm is:

  • A) 525\sqrt{2}52​ cm
  • B) 535\sqrt{3}53​ cm
  • C) 10 cm
  • D) 5 cm

Answer: A) 525\sqrt{2}52​ cm
The length of the diagonal of a square is side×2\text{side} \times \sqrt{2}side×2​. For side = 5 cm, the diagonal is 525\sqrt{2}52​ cm.

33. The value of 4+6×2−34 + 6 \times 2 – 34+6×2−3 is:

  • A) 9
  • B) 11
  • C) 7
  • D) 10

Answer: B) 11
Using the order of operations (BODMAS), 6×2=126 \times 2 = 126×2=12, so 4+12−3=134 + 12 – 3 = 134+12−3=13.

34. What is the area of a rectangle with length 12 cm and width 6 cm?

  • A) 72 cm²
  • B) 18 cm²
  • C) 36 cm²
  • D) 48 cm²

Answer: A) 72 cm²
The area of a rectangle is length×width\text{length} \times \text{width}length×width. So, 12×6=7212 \times 6 = 7212×6=72 cm².

35. What is the ratio of the areas of two squares with side lengths 5 cm and 10 cm?

  • A) 1:2
  • B) 1:4
  • C) 1:3
  • D) 1:5

Answer: B) 1:4
The area of a square is proportional to the square of the side. The ratio of areas is (52):(102)=25:100=1:4(5^2):(10^2) = 25:100 = 1:4(52):(102)=25:100=1:4.

36. A number is increased by 20% of its value. If the number is 50, the increased value is:

  • A) 55
  • B) 60
  • C) 70
  • D) 80

Answer: B) 60
The increase is 20%20\%20% of 50, which is 50×0.20=1050 \times 0.20 = 1050×0.20=10. So, the increased value is 50+10=6050 + 10 = 6050+10=60.

37. The surface area of a sphere with a radius of 6 cm is:

  • A) 144π144\pi144π cm²
  • B) 36π36\pi36π cm²
  • C) 72π72\pi72π cm²
  • D) 24π24\pi24π cm²

Answer: A) 144π144\pi144π cm²
The surface area of a sphere is 4πr24\pi r^24πr2. For r=6r = 6r=6, the surface area is 4π×62=144π4\pi \times 6^2 = 144\pi4π×62=144π cm².

38. If the cost of 5 books is Rs 200, what is the cost of 8 books?

  • A) Rs 320
  • B) Rs 380
  • C) Rs 400
  • D) Rs 420

Answer: A) Rs 320
The cost per book is 200÷5=40200 \div 5 = 40200÷5=40 Rs. So, the cost of 8 books is 40×8=32040 \times 8 = 32040×8=320 Rs.

39. What is the value of xxx in the equation 3x+7=163x + 7 = 163x+7=16?

  • A) 3
  • B) 4
  • C) 2
  • D) 5

Answer: B) 3
Solving 3x+7=163x + 7 = 163x+7=16, we get 3x=93x = 93x=9, so x=3x = 3x=3.

40. The perimeter of an equilateral triangle with side length 7 cm is:

  • A) 21 cm
  • B) 28 cm
  • C) 24 cm
  • D) 30 cm

Answer: A) 21 cm
The perimeter of an equilateral triangle is 3×side3 \times \text{side}3×side. So, 3×7=213 \times 7 = 213×7=21 cm.

These are some more MCQs for Class 8 Maths. Let me know if you’d like more!

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