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A reddish-brown metal… (Class 10 Science SQP 2023-24, Q28b)

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ScienceCBSE Class 10 · Sample paper, session 2023-24 · 3 marks · Short answer

CBSE Class 10 Science sample paper 2023-24: question 28(b)

From the official CBSE sample question paper for 2023-24, section C, question 28(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28(b) · 3 marks · Short answerMetals and Non-metals

A reddish-brown metal 'X', when heated in air, gives a black compound 'Y', which when heated in presence of gas gives 'X' back. 'X' is refined by the process of electrolysis; this refined form of 'X' is used in electrical wiring.
Identify 'X' and 'Y'. Draw a well-labeled diagram to represent the process of refining 'X'.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

Which reddish-brown metal is used in electric wires?

Hint 2

In electrolytic refining, the impure metal is made the anode and a thin strip of pure metal is 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. X is a reddish-brown metal used in electrical wiring, so X = Copper (Cu). On heating in air: , so Y = Copper(II) oxide, CuO (black). With hydrogen: .

    1 mark

  2. Diagram of electrolytic refining of copper (to be drawn and labelled): a tank containing acidified copper sulphate solution (electrolyte). A thick block of impure copper is the anode, connected to the positive terminal of the battery. A thin strip of pure copper is the cathode, connected to the negative terminal. A battery and a key complete the circuit. Show ions moving towards the cathode, and anode mud (impurities) collecting at the bottom below the anode.

    1½ marks

  3. Working: at the anode, . At the cathode, , so pure copper is deposited on the cathode. Insoluble impurities settle as anode mud.

    ½ mark

Answer: X = Copper (Cu), Y = Copper(II) oxide (CuO); refining by electrolysis with an impure Cu anode, a pure Cu cathode and acidified electrolyte.

Where the marks are

  • Identifies X as Cu and Y as CuO (1 mark)
  • Diagram with correct labels: impure Cu anode (+), pure Cu cathode (−), acidified solution, anode mud, battery/key (2 marks)

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 2023-24: 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.