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In an activity Aishu… (Class 10 Science SQP 2024-25, Q27B)

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ScienceCBSE Class 10 · Sample paper, session 2024-25 · 3 marks · Short answer

CBSE Class 10 Science sample paper 2024-25: question 27(B)

From the official CBSE sample question paper for 2024-25, section C, question 27(B), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27(B) · 3 marks · Short answerMetals and Non-metals

In an activity Aishu was given two substances; Copper Sulphide () and Copper Oxide () to obtain copper from these compounds. She was able to extract Copper successfully. Illustrate with the help of chemical equations how Aishu might have completed the activity.

(For visually impaired students: Give reasons for the following
i. Certain metals are used for making cooking utensils.
ii. Hydrogen gas does not evolve when certain metals except Mg & Mn react with nitric acid.)

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

Where is copper in the reactivity series? Is carbon needed to reduce its compounds?

Hint 2

Heating a sulphide ore in air is called roasting. What does Cu₂S form?

Hint 3

The oxide formed can react with the remaining sulphide when heated.

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. Copper is low in the reactivity series, so its compounds can be reduced to the metal by heating alone (self-reduction). First, heat copper sulphide strongly in air (roasting) so that part of it changes to copper(I) oxide:

    1 mark

  2. Then heat the copper(I) oxide with the remaining copper sulphide in the absence of air, which reduces it to copper:

    1 mark

  3. Here is reduced (it loses oxygen) and the sulphide is oxidised to , so copper is obtained by heating alone, without any other reducing agent.

    1 mark

  4. (For visually impaired students) i. Metals such as aluminium and copper are used for cooking utensils because they are good conductors of heat and have high melting points. ii. Nitric acid is a strong oxidising agent. It oxidises the produced to water and is itself reduced to nitrogen oxides (N₂O, NO, NO₂). Only Mg and Mn give with very dilute HNO₃.

Answer: 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂ (roasting); 2Cu₂O + Cu₂S → 6Cu + SO₂ (self-reduction).

Where the marks are

  • Balanced roasting equation of Cu₂S to Cu₂O (1 mark)
  • Balanced self-reduction equation giving Cu (1 mark)
  • Explains reduction by heating alone because copper is low in the reactivity series (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 paperSample paper 2024-25: 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.