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In which one of the following… (Class 10 Science 2025, Q1)

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ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 1 mark · MCQ

CBSE Class 10 Science 2025: question 1

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

Q1 · 1 mark · MCQChemical Reactions and Equations

In which one of the following situations a chemical reaction does not occur?

  1. (A)Milk is left open at room temperature during summer
  2. (B)Grapes get fermented
  3. (C)An iron nail is left exposed to humid atmosphere
  4. (D)Melting of glaciers

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

Ask which change produces a new substance.

Hint 2

A change of state is not a chemical reaction.

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. Souring of milk, fermentation of grapes and rusting of iron all form new substances, so they are chemical changes.

  2. Melting of glaciers only changes ice to water (a change of state). No new substance forms, so it is a physical change. Option (D).

    1 mark

Answer: (D) Melting of glaciers

Where the marks are

  • Identifies melting of glaciers as a physical change (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.