Skip to content

Read the following passage and… (Science 2026 31/3/1 Q28)

questionbuddy.in/q/cbse-10-science-2026-31-3-1-q28-electrochemical-process-used-refining-metals

ScienceCBSE Class 10 · Board exam 2026, set 31/3/1 · 4 marks · Case-based

CBSE Class 10 Science 2026: question 28

Set in the CBSE Class 10 board exam of 2026, paper 31/3/1, section B, question 28, for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q28 · 4 marks · Case-basedCompetency-basedMetals and Non-metals

Read the following passage and answer the questions that follow :

An electrochemical process is used for refining metals by selectively dissolving and depositing them through electrolysis. Electrolytic refining is used for metals like Copper, Zinc, Tin, Nickel, Silver and Gold.

  1. (a)

    Define anode mud.

    1 mark
  2. (b)

    In electrolytic refining of copper, name the anode and the cathode.

    1 mark
  3. (c)(i)

    With the help of chemical equations, show the extraction of copper from its ore .

    2 marks

  4. OR

    (c)(ii)

    Draw a neat and labelled diagram showing electrolytic refining of copper.

    2 marks

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

Impurities that do not dissolve drop to the bottom near one electrode. Which one?

Hint 2

The metal to be purified dissolves, so it must be the electrode that loses copper. For (c), remember the ore is first roasted and then reduces itself.

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. (a) During electrolytic refining, the insoluble impurities that settle at the bottom, below the anode, are called anode mud.

    1 mark

  2. (b) Anode: a thick rod of impure copper.

    ½ mark

  3. Cathode: a thin strip of pure copper.

    ½ mark

  4. (c)(i) Roasting: the sulphide ore is partly heated in air:

    1 mark

  5. Self-reduction: the copper(I) oxide then reacts with the remaining :

    1 mark

  6. (c)(ii) (Alternative to (c)(i), 2 marks: diagram 1, labels 1.) Draw an electrolytic tank containing acidified copper sulphate solution, with two electrodes dipped in it and connected to a battery through a switch. The thick impure copper rod is joined to the positive terminal and the thin pure copper strip to the negative terminal. Anode mud is shown at the bottom below the anode. Labels: Anode (impure copper), Cathode (pure copper), Acidified copper sulphate solution (electrolyte), Anode mud, Battery / + and − terminals, Tank.

Answer: (a) Insoluble impurities settling below the anode; (b) Anode: impure copper, Cathode: pure copper; (c)(i) 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂, then 2Cu₂O + Cu₂S → 6Cu + SO₂; (c)(ii) labelled electrolytic refining set-up.

Where the marks are

  • Correct definition of anode mud (1 mark)
  • Anode: impure copper (½ mark); Cathode: pure copper (½ mark)
  • Roasting equation (1 mark) and self-reduction equation (1 mark), OR diagram (1 mark) with labels (1 mark)

Revise the chapter

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 31/3/1: 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.