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Assertion (A): Concentrated… (Class 10 Science 2025, Q18)

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ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2025: question 18

Set in the CBSE Class 10 board exam of 2025, paper 31/4/1, section A, question 18, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q18 · 1 mark · Assertion-reasonCompetency-basedAcids, Bases and Salts

Assertion (A): Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring.

Reason (R): Concentrated nitric acid is easily soluble in water.

  1. (A)Both, Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  2. (B)Both, Assertion (A) and Reason (R) are true, and Reason (R) is not the correct explanation of 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 2025 board paper, set 31/4/1.

Hints

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

Hint 1

Recall the safe order for mixing acid and water.

Hint 2

Is the dilution exothermic?

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. A is false: an acid is diluted by adding the acid slowly to water, never water to acid, because the process is highly exothermic.

  2. R is true: concentrated nitric acid dissolves readily in water. Option (D).

    1 mark

Answer: (D) A false, R true

Where the marks are

  • A false, R true (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Acids, Bases and Salts, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 31/4/1: 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.