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Explain chlor-alkali process… (Class 10 Science 2026, Q27a)

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

CBSE Class 10 Science 2026: question 27(a)

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

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

Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode.

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

Hints

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

Hint 1

The name comes from the products: chlor + alkali.

Hint 2

Negative ions move to the anode and H⁺ is reduced at the cathode.

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. When electricity is passed through brine (an aqueous solution of sodium chloride), it decomposes to give sodium hydroxide (an alkali) and chlorine. Because the products are chlorine and an alkali, the process is called the chlor-alkali process.

    1 mark

  2. Equation:

    1 mark

  3. At the anode: chlorine gas () is formed.

    ½ mark

  4. At the cathode: hydrogen gas () is formed. Sodium hydroxide solution collects near the cathode.

    ½ mark

Answer: Electrolysis of brine gives NaOH, Cl₂ and H₂; Cl₂ at anode, H₂ at cathode

Where the marks are

  • Explains the process and the reason for its name (1 mark)
  • Balanced chemical equation (1 mark)
  • Cl₂ at anode (½ mark)
  • H₂ at cathode (½ mark)

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 31/1/1: 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.