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

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

CBSE Class 10 Science 2026: question 28

Set in the CBSE Class 10 board exam of 2026, paper 31/1/1, 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 given below:
Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like – Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals.

  1. (a)

    Why carbonate or sulphide ores are converted to oxides before extraction of metal from it?

    1 mark
  2. (b)

    Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide.

    1 mark
  3. (c)(i)

    How is copper obtained from its ore (Cu2S)? Give equations of the reactions.

    2 marks
  4. (c)(ii)(I)

    Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent?

    1 mark
  5. (c)(ii)(II)

    Why solder, an alloy of lead and tin, is used for welding electrical wires together?

    1 mark

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

Which compound is the easiest for carbon to reduce?

Hint 2

For copper, part of the sulphide is first turned into oxide, which then reacts with the rest of the sulphide.

Hint 3

Compare how strongly reactive metals and carbon hold on to oxygen.

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) It is easier to obtain a metal from its oxide than from its carbonate or sulphide, because a metal oxide can be reduced readily by carbon. So carbonate ores are calcined and sulphide ores are roasted to convert them into oxides first.

    1 mark

  2. (b) Thermit reaction:

    1 mark

  3. (c)(i) Copper glance () is roasted in air, which converts part of it to copper(I) oxide:

    1 mark

  4. (c)(i) The formed then reacts with the remaining (self-reduction) to give copper metal:

    1 mark

  5. (c)(ii)(I) [OR alternative] Highly reactive metals such as Na, Mg and Al have a greater affinity for oxygen than carbon has. So carbon cannot remove oxygen from their oxides, and these metals are obtained by electrolytic reduction instead.

    1 mark

  6. (c)(ii)(II) [OR alternative] Solder has a low melting point, lower than that of the pure metals lead and tin. So it melts easily and can be used to join electrical wires.

    1 mark

Answer: (a) Oxides are easier to reduce to metal; (b) Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat; (c)(i) 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂, then 2Cu₂O + Cu₂S → 6Cu + SO₂; OR (c)(ii) (I) these metals have more affinity for oxygen than carbon; (II) solder has a low melting point

Where the marks are

  • Oxides are easier to reduce to metal (1 mark)
  • Any correct thermit-type equation (1 mark)
  • Roasting equation for Cu₂S (1 mark)
  • Self-reduction equation giving Cu (1 mark)
  • OR: greater affinity for oxygen than carbon (1 mark); low melting point of solder (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 31/1/1: 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.