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Write the preparation of the… (Class 10 Science 2026, Q27b)

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ScienceCBSE Class 10 · Board exam 2026, set 31/3/1 · 3 marks · Short answer

CBSE Class 10 Science 2026: question 27(b)

Set in the CBSE Class 10 board exam of 2026, paper 31/3/1, section B, question 27(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27(b) · 3 marks · Short answerAcids, Bases and Salts

Write the preparation of the following compounds with balanced chemical equation :

  1. (i)

    NaOH by chlor-alkali process

    1 mark
  2. (ii)

    Baking Soda

    1 mark
  3. (iii)

    Plaster of Paris

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/3/1.

Hints

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

Hint 1

Chlor-alkali means passing electricity through brine. Which three products form?

Hint 2

Baking soda needs ammonia and CO₂ with brine. Plaster of Paris is gypsum that has lost part of its water on heating.

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) Chlor-alkali process: electricity is passed through an aqueous solution of NaCl (brine). gas forms at the anode, gas at the cathode, and NaOH solution near the cathode:

    1 mark

  2. (ii) Baking soda is made from sodium chloride, water, ammonia and carbon dioxide:

    1 mark

  3. (iii) Plaster of Paris is made by heating gypsum at 373 K:

    1 mark

Answer: (i) 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂ (electrolysis); (ii) NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃; (iii) CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O at 373 K.

Where the marks are

  • Balanced chlor-alkali equation (1 mark)
  • Balanced equation for baking soda (1 mark)
  • Balanced equation for Plaster of Paris at 373 K (1 mark); ½ deducted in each case if unbalanced

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 paper2026 board paper, set 31/3/1: 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.