Which of the following are chemical changes ?
(a) Growth of a plant
(b) Rusting of iron
(c ) Mixing of iron filings and sand
(d) Cooking of food
(e ) Digestion of food
(f) Freezing of water
(g) Burning of a candle

Explanation

To determine which of the given processes are chemical changes, we will analyze each option one by one:

1. **Growth of a plant**:
- This process involves biological changes where plants undergo photosynthesis and other metabolic processes. While there are chemical reactions involved, it is primarily classified as a biological change.
- **Conclusion**: Not a chemical change.

2. **Rusting of iron**:
- Rusting is an electrochemical process where iron reacts with oxygen and moisture in the environment to form iron oxide (rust). This involves a chemical reaction and results in the formation of a new substance.
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