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Which of the following is NOT a rational number? (a) 0.75 (b) 2/3 (c) √2 (d) 5/2

hard MCQ 3 marks Class 7 · Mathematics · Rational Numbers
  1. a) 0.75
  2. b) 2/3
  3. c) √2
  4. d) 5/2
Answer
c) √2

The correct answer is c) √2 — 5/2 is a fraction of integers → rational.

Step-by-step solution

  1. Recall that a rational number can be expressed as a fraction of two integers with a non-zero denominator.
  2. Check each option: 0.75 = 75/100 = 3/4 → rational.
  3. 2/3 is a fraction of integers → rational.
  4. √2 cannot be expressed as a fraction of two integers (known irrational) → not rational.
  5. 5/2 is a fraction of integers → rational.
Common mistake: Assuming all square roots are rational

Concept tested: Identifying rational versus irrational numbers

Published · How this solution was prepared and checked

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