Class 9th Number Systems MCQs

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1. Which of the following is an irrational number?
   a) 7/4
   b) 0.75
   c) √5
   d) 0.333…
2. The decimal expansion of a rational number is always:
   a) Terminating or repeating
   b) Non-terminating, non-repeating
   c) Terminating only
   d) None of these
3. What is the rational number representation of 0.121212…?
   a) 12/99
   b) 11/90
   c) 12/90
   d) 11/99
4. Which of the following is a rational number?
   a) π
   b) √2
   c) 3.1415
   d) 5/8
5. What is the value of (√3 + √2)(√3 − √2)?
   a) 1
   b) 5
   c) √5
   d) √6
6. Which of the following is NOT a rational number?
   a) 5
   b) -3
   c) √7
   d) 0.25
7. The sum of two rational numbers is always:
   a) Rational
   b) Irrational
   c) Either rational or irrational
   d) None of these
8. The product of two irrational numbers can be:
   a) Only irrational
   b) Only rational
   c) Either rational or irrational
   d) None of these
9. If x = 0.999…, then x is equal to:
   a) 1
   b) 0.999
   c) 0.9
   d) None of these
10. Which of the following is an example of a terminating decimal?
    a) 0.666…
    b) 0.125
    c) 0.142857…
    d) 0.333…
11. The number 3/11 in decimal form is:
    a) Terminating decimal
    b) Non-terminating repeating decimal
    c) Non-terminating non-repeating decimal
    d) None of these
12. Which of the following can be represented exactly on the number line?
    a) √2
    b) π
    c) 1/2
    d) Both a and c
13. The rational number between 1/2 and 3/4 is:
    a) 5/8
    b) 1/4
    c) 2/3
    d) 7/8
14. Which property states that (a + b) + c = a + (b + c)?
    a) Commutative property
    b) Associative property
    c) Distributive property
    d) Identity property
15. If a rational number has denominator 2^m × 5^n (m,n ≥ 0), its decimal expansion will:
    a) Terminate
    b) Repeat
    c) Be non-terminating non-repeating
    d) None of these
16. The conjugate of (√5 + √3) is:
    a) (√5 + √3)
    b) (√5 − √3)
    c) (−√5 + √3)
    d) None of these
17. Which of the following is the simplest form of 0.454545…?
    a) 45/100
    b) 5/11
    c) 45/99
    d) 50/99
18. The irrational numbers are:
    a) Countable
    b) Uncountable
    c) Finite
    d) None of these
19. The square root of a prime number is always:
    a) Rational
    b) Irrational
    c) Whole number
    d) None of these
20. Which of the following pairs are both irrational?
    a) √2 and √3
    b) √4 and √9
    c) 2/3 and 5/7
    d) 0.333… and 1.25

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Answers:

1. c) √5
2. a) Terminating or repeating
3. a) 12/99
4. d) 5/8
5. b) 5
6. c) √7
7. a) Rational
8. c) Either rational or irrational
9. a) 1
10. b) 0.125
11. b) Non-terminating repeating decimal
12. d) Both a and c
13. a) 5/8
14. b) Associative property
15. a) Terminate
16. b) (√5 − √3)
17. b) 5/11
18. b) Uncountable
19. b) Irrational
20. a) √2 and √3

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