Class 9 Maths MCQ – Number Systems

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1. Which of the following is an irrational number?

a) 1/7
b) 2.5
c) √2
d) 0.333…

Answer:

c) √2

Explanation:

√2 cannot be expressed as a fraction, making it irrational.

2. Which number is both irrational and rational?

a) 0.5
b) 3.14
c) 2.333…
d) None of the above

Answer:

d) None of the above

Explanation:

A number cannot be both irrational and rational at the same time.

3. The decimal expansion of the rational number 3/8 is:

a) 0.38
b) 0.375
c) 0.833…
d) 3.08

Answer:

b) 0.375

Explanation:

Dividing 3 by 8 gives 0.375.

4. Which of the following is not a rational number?

a) -5
b) 0
c) 1/3
d) π

Answer:

d) π

Explanation:

π (Pi) is an irrational number.

5. The value of √144 is:

a) 14
b) 12
c) 72
d) 288

Answer:

b) 12

Explanation:

The square root of 144 is 12.

6. Which number system includes all other number systems?

a) Natural numbers
b) Integers
c) Rational numbers
d) Real numbers

Answer:

d) Real numbers

Explanation:

Real numbers include rational, irrational, integers, and natural numbers.

7. Which of the following is a terminating decimal?

a) 4/7
b) 7/8
c) 1/9
d) 2/11

Answer:

b) 7/8

Explanation:

7 divided by 8 gives 0.875, which is terminating.

8. The decimal expansion of 1/7 is:

a) 0.142857…
b) 0.7
c) 0.1666…
d) 0.714285…

Answer:

a) 0.142857…

Explanation:

1 divided by 7 results in a repeating decimal of 0.142857…

9. Every natural number is also a:

a) Whole number
b) Irrational number
c) Integer
d) Both a and c

Answer:

d) Both a and c

Explanation:

All natural numbers are whole numbers and integers.

10. Which of the following is not a whole number?

a) -1
b) 0
c) 1
d) 1000

Answer:

a) -1

Explanation:

Whole numbers start from 0 and include all positive integers.

11. The value of -√49 is:

a) 7
b) -7
c) -49
d) 49

Answer:

b) -7

Explanation:

The square root of 49 is 7. With the negative sign, it's -7.

12. What type of decimal expansion does the number 5/11 have?

a) Terminating
b) Non-terminating repeating
c) Non-terminating non-repeating
d) None of the above

Answer:

b) Non-terminating repeating

Explanation:

5/11 is 0.454545…

13. The product of a rational and an irrational number is:

a) Rational
b) Irrational
c) Either rational or irrational
d) None of the above

Answer:

c) Either rational or irrational

Explanation:

If the rational number is zero, the product is rational (0). Otherwise, it's irrational.

14. Which of these numbers is closest to the value of π?

a) 3.12
b) 3.14
c) 3.141
d) 3.15

Answer:

b) 3.14

Explanation:

π is approximately 3.14159…

15. If a number is irrational, its square:

a) Must be irrational
b) Must be rational
c) Can be either rational or irrational
d) Is always a prime number

Answer:

c) Can be either rational or irrational

Explanation:

For instance, (√2)^2 = 2, which is rational.

16. The smallest natural number is:

a) 0
b) 1
c) -1
d) 2

Answer:

b) 1

Explanation:

Natural numbers start from 1.

17. Which of the following is an integer?

a) -3.5
b) √3
c) 4/5
d) -7

Answer:

d) -7

Explanation:

-7 is a whole number and thus an integer.

18. Which number is not considered a real number?

a) Imaginary numbers
b) Rational numbers
c) Irrational numbers
d) Integers

Answer:

a) Imaginary numbers

Explanation:

Imaginary numbers, like the square root of -1, are not real numbers.

19. Which of these is a property of rational numbers?

a) They can always be expressed in fraction form.
b) They have a non-repeating decimal part.
c) They cannot be negative.
d) They include all irrational numbers.

Answer:

a) They can always be expressed in fraction form.

Explanation:

Rational numbers can be expressed as a ratio of two integers.

20. The sum of two irrational numbers:

a) Is always irrational
b) Is always rational
c) Can be either rational or irrational
d) Is always a whole number

Answer:

c) Can be either rational or irrational

Explanation:

For example, √2 + (-√2) = 0, which is rational.

Related MCQ (Multiple Choice Questions) :

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