Lesson eLearning

A piece of iron is left outside and after a few weeks it turns brown. Is this change physical or chemical? Explain.

easy 2 marks Class 7 · Science · Physical and Chemical Changes
Answer
Chemical change.

The correct answer is Chemical change. — Conclude that this is a chemical change because a new substance is formed.

Step-by-step solution

  1. Define physical change – no new substance is formed, only change in state or appearance.
  2. Define chemical change – a new substance is formed with different properties.
  3. Observe that the iron turns brown to rust, which is a new compound, Fe₂O₃.
  4. Conclude that this is a chemical change because a new substance is formed.
Common mistake: Thinking the colour change alone indicates a chemical change

Concept tested: Identifying chemical change by formation of new substance

Published · How this solution was prepared and checked

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