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Science — CBSE Class 10 board question

Q1. [1]
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
Previously asked in CBSE board exam
2025 31/4/1 Q1
Generated by claude-sonnet-4-6 · 2026-06-14 10:29 · grounding rag
Model Answer

(d) Melting of glaciers

Melting of glaciers is a physical change (change of state from solid to liquid); no new substance is formed, so no chemical reaction occurs.

Explanation

The textbook's Chapter 1 introduction lists milk souring, iron rusting, and grape fermentation as examples where chemical reactions take place (identity of substance changes). Melting is purely a physical change — only the state changes, not the chemical composition. Examiners expect students to distinguish physical changes from chemical reactions.

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Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.