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Assertion (A): Onion… (Class 10 Science SQP 2026-27, Q24)

questionbuddy.in/q/cbse-10-science-2026-27-sqp-q24-onion-loses-smell-added-baking

ScienceCBSE Class 10 · Sample paper, session 2026-27 · 1 mark · Assertion-reason

CBSE Class 10 Science sample paper 2026-27: question 24

From the official CBSE sample question paper for 2026-27, 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-basedAcids, Bases and Salts

Assertion (A): Onion extract loses its smell, when it is added to baking soda solution whereas it retains its smell when added to lemon juice. Reason (R): Onion acts as an olfactory indicator.

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

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Is baking soda acidic or basic? Is lemon juice acidic or basic?

Hint 2

Does R explain why the smell disappears, or does it only classify onion?

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. Assertion A is true: baking soda solution is basic, and onion loses its smell in a base. Lemon juice is acidic, so the smell remains.

    ½ mark

  2. Reason R is also true, since onion is an olfactory indicator. However, R only names the type of indicator and does not explain why the smell is lost in a base. So the answer is (B).

    ½ mark

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

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 paperSample paper 2026-27: 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.