ScienceCBSE Class 10 · Board exam 2026, set 31/2/1 · 2 marks · Very short answer

CBSE Class 10 Science 2026: question 25

Set in the CBSE Class 10 board exam of 2026, paper 31/2/1, section B, question 25, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25 · 2 marks · Very short answerCompetency-basedMetals and Non-metals

Read the following passage and answer the questions that follow :

One student was comparing the reactivity of different metals for his science project. He added iron filings in four test tubes A, B, C and D containing aqueous solutions of $Z n S O_{4}$ , $C u S O_{4}$ , $F e S O_{4}$ and $A l_{2} (S O_{4})_{3}$ .

(i)
In which of the test tubes will he observe the reaction to be the most vigorous and why ?
1 mark
(ii)
Write a balanced equation for the reaction involved.
1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/2/1.

Hints

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

Hint 1

Use the reactivity series: where is iron compared with Zn, Cu and Al?

Hint 2

A metal can displace only a less reactive metal from its salt solution.

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.

(i) The reaction occurs in test tube B ( $C u S O_{4}$ solution).
½ mark
Reason: iron is more reactive than copper, so it displaces copper from copper sulphate solution. Iron is less reactive than Zn and Al and cannot displace itself from $F e S O_{4}$ , so no reaction occurs in A, C and D.
½ mark
(ii) $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$
The blue solution turns pale green and reddish-brown copper is deposited.
1 mark

Answer: (i) Test tube B, as iron is more reactive than copper and displaces it; (ii) $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$

Where the marks are

Identifies test tube B (½ mark)
Reason: Fe is more reactive than Cu and displaces it (½ mark)
Correct balanced equation (1 mark)

Revise the chapter

Chapter: Metals and Non-metals (notes, formulas, where marks are lost and every past question)

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 paper2026 board paper, set 31/2/1: every question, by section.

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CBSE Class 10 Science 2026: question 25

Hints

Step-by-step solution

Revise the chapter

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