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Write balanced chemical… (Class 10 Science 2023, Q21b)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 2 marks · Very short answer

CBSE Class 10 Science 2023: question 21(b)

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section B, question 21(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21(b) · 2 marks · Very short answerChemical Reactions and Equations

Write balanced chemical equation for the reaction that occurs when :

  1. (i)

    blue coloured copper sulphate crystals are heated and

    0 marks
  2. (ii)

    Sodium hydrogen carbonate is heated during cooking.

    0 marks

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

Blue copper sulphate crystals contain 5 molecules of water of crystallisation.

Hint 2

Heating baking soda produces a gas that makes dough rise. Balance the sodium atoms.

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) On heating, the blue crystals lose their water of crystallisation and turn into white anhydrous copper sulphate:

    1 mark

  2. (ii) On heating, baking soda decomposes to sodium carbonate, water and carbon dioxide:

    1 mark

Answer: (i) CuSO₄·5H₂O → CuSO₄ + 5H₂O; (ii) 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

Where the marks are

  • Balanced dehydration equation of blue vitriol (1 mark)
  • Balanced decomposition equation of (1 mark)

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 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.