CBSE Class 10 Mathematics Standard sample paper 2024-25: question 19
From the official CBSE sample question paper for 2024-25, section A, question 19, for 1 mark. Try it first; the hints and our step-by-step solution are below.
Q19 · 1 mark · Assertion-reasonCompetency-basedReal Numbers
Direction: In the question number 19 and 20, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option.
Assertion (A): HCF of any two consecutive even natural numbers is always 2.
Reason (R): Even natural numbers are divisible by 2.
- (A)Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A)
- (B)Both assertion (A) and reason (R) are true and reason (R) is not the correct explanation of assertion (A)
- (C)Assertion (A) is true but reason (R) is false.
- (D)Assertion (A) is false but reason (R) is true.
Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.
Hints
Open one hint at a time and try again before the next.
Hint 1
Write two consecutive even numbers as and .
Hint 2
Does 'divisible by 2' alone prove that the HCF is exactly 2?
Step-by-step solution
Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.
Consecutive even numbers are and . Their HCF is , so (A) is true.
- 1 mark
(R) is true. However, divisibility by 2 only shows that 2 is a common factor; it does not show that there is no larger common factor. So (R) does not explain (A). The answer is option (B).
Answer: Option (B)
Where the marks are
- Judges both A and R true, with R not the correct explanation of A (1 mark)
Revise the chapter
- Chapter: Real Numbers (notes, formulas, where marks are lost and every past question)
- Topic: HCF and LCM by Prime Factorisation
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