Melting, freezing and evaporation are all physical changes because they:
Arelease energy as heat and light
Bcan be reversed and form no new substance
Calways produce a gas as the product
Dinvolve a change in the atomic nucleus
Answer & Solution
Correct answer: B. can be reversed and form no new substance
1. The test for a physical change is whether a new substance appears.
2. Melting, freezing and evaporation only alter the state of the same substance.
3. Each can be reversed: liquid butter refreezes, water vapour condenses, frozen juice melts.
4. No new substance forms at any point, which is what makes them physical.
5. Composting is different because the decomposed material cannot be turned back into food scraps.
_Source: NECTA CSEE 2021 Chemistry 032, Question 1: Multiple Choice, item (iii)_
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