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Define oxidation. Identify… (Class 10 Science 2025, Q21)

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ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 2 marks · Very short answer

CBSE Class 10 Science 2025: question 21

Set in the CBSE Class 10 board exam of 2025, paper 31/4/1, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerChemical Reactions and Equations

Define oxidation. Identify and name the substance oxidised in the following reaction :

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/4/1.

Hints

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

Hint 1

Recall the definition of oxidation in terms of oxygen or hydrogen.

Hint 2

Look at which reactant ends up with extra oxygen in the products.

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. Oxidation is a reaction in which a substance gains oxygen or loses hydrogen (in terms of electrons, it loses electrons).

    1 mark

  2. In , hydrogen gains oxygen to form water. So the substance oxidised is **hydrogen ()**. CuO loses oxygen and is reduced.

    1 mark

Answer: Oxidation is gain of oxygen or loss of hydrogen; the substance oxidised is hydrogen ().

Where the marks are

  • Correct definition of oxidation as gain of oxygen, loss of hydrogen or loss of electrons (1 mark)
  • Identifies (hydrogen) as the substance oxidised (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemical Reactions and Equations, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 31/4/1: 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.