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What happens when : (i) lead… (Class 10 Science 2026, Q26)

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ScienceCBSE Class 10 · Board exam 2026, set 31/5/1 · 3 marks · Very short answer

CBSE Class 10 Science 2026: question 26

Set in the CBSE Class 10 board exam of 2026, paper 31/5/1, section B, question 26, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q26 · 3 marks · Very short answerChemical Reactions and Equations

What happens when :
(i) lead (II) nitrate is heated ?
(ii) iron (II) sulphate is heated ?
(iii) silver chloride is exposed to sunlight ?

Write balanced chemical equations of the reactions involved in support of your answer.

  1. (i)

    What happens when lead (II) nitrate is heated ? Write balanced chemical equation.

    1 mark
  2. (ii)

    What happens when iron (II) sulphate is heated ? Write balanced chemical equation.

    1 mark
  3. (iii)

    What happens when silver chloride is exposed to sunlight ? Write balanced chemical equation.

    1 mark

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

All three are decomposition reactions — two by heat, one by light.

Hint 2

Check each equation's balance: count Pb, N, O; Fe, S, O; Ag, Cl on both sides.

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. (i) Lead nitrate decomposes on heating and brown fumes of nitrogen dioxide are given off; yellow lead oxide remains.

    1 mark

  2. (ii) Green ferrous sulphate crystals change colour, forming reddish-brown ferric oxide with a smell of burning sulphur.

    1 mark

  3. (iii) White silver chloride turns grey as silver metal forms and chlorine is released.

    1 mark

Answer: (i) Brown NO₂ fumes: 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂; (ii) burning-sulphur smell, colour change: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃; (iii) white AgCl turns grey: 2AgCl → 2Ag + Cl₂

Where the marks are

  • Observation and balanced equation for Pb(NO₃)₂ (½ + ½ marks)
  • Observation and balanced equation for FeSO₄ (½ + ½ marks)
  • Observation and balanced equation for AgCl (½ + ½ marks)

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.