Question

which one among the following represents a physical change? a rusting of iron b decomposition of organic matter c burning of a candle d melting of wax

Explanation:

To determine a physical change, we recall that physical changes involve a change in state or appearance without forming new substances.

• Option a: Rusting of iron forms iron oxide (new substance), so it's a chemical change.
• Option b: Decomposition of organic matter breaks it into new substances (like CO₂, H₂O), chemical change.
• Option c: Burning a candle involves wax combustion (new substances: CO₂, H₂O) and melting (physical), but overall burning is chemical.
• Option d: Melting of wax changes solid wax to liquid wax; no new substance is formed, just a state change (physical change).

Answer:

d. Melting of wax