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Assertion (A) : The colour of… (Class 10 Science 2023, Q17)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2023: question 17

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section A, question 17, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q17 · 1 mark · Assertion-reasonCompetency-basedMetals and Non-metals

Assertion (A) : The colour of aqueous solution of copper sulphate turns colourless when a piece of lead is added to it.
Reason (R) : Lead is more reactive than copper, and hence displaces copper from its salt solution.

  1. (A)Both (A) and (R) are true and (R) is the correct explanation of (A).
  2. (B)Both (A) and (R) are true, but (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 question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/1/1.

Hints

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

Hint 1

Compare the positions of Pb and Cu in the reactivity series.

Hint 2

What gives copper sulphate solution its blue colour?

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. Lead is above copper in the reactivity series, so it displaces copper: . Reason (R) is true.

  2. Because copper ions are removed from the solution, the blue colour fades. So (A) is true and (R) explains it, option (A).

    1 mark

Answer: Option (A)

Where the marks are

  • Both true and R correctly explains A (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Metals and Non-metals, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/1/1: 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.