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In the question two… (Class 10 Science 2026, Q24)

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ScienceCBSE Class 10 · Board exam 2026, set 31/5/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2026: question 24

Set in the CBSE Class 10 board exam of 2026, paper 31/5/1, section B, question 24, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q24 · 1 mark · Assertion-reasonCompetency-basedChemical Reactions and Equations

In the question two statements are given – one labelled as Assertion (A) and other labelled as Reason (R). Answer this question selecting the appropriate option from (A), (B), (C) and (D) given below.

Assertion (A): Reaction of quick lime with water is an exothermic reaction.

Reason (R): A large amount of heat is evolved on the reaction of quick lime and water.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Define an exothermic reaction.

Hint 2

Does R give the defining feature of that type of reaction?

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.

  1. The reaction is + heat, so A is true.

  2. R is true, and release of a large amount of heat is what makes a reaction exothermic, so R explains A. Answer: (A).

    1 mark

Answer: (A)

Where the marks are

  • Both true, R explains A (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemical Reactions and Equations, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.