Which among the following is not a physical change?

Options

A. Evaporation of petrol
B. Burning of liquified petroleum gas (LPG)
C. Heating of an iron rod to red hot.
D. Sublimation of solid ammonium chloride

Explanation

To determine which among the following options is not a physical change, we need to analyze each option based on the definitions of physical and chemical changes.

### Step-by-Step Solution:

1. **Understanding Physical Changes**:
- A physical change is a change that does not alter the chemical composition of a substance. It may involve changes in state (solid, liquid, gas), shape, or size but does not produce new substances.

2. **Understanding Chemical Changes**:
- A chemical change involves a transformation that results in the formation of one or more new substances with different chemical properties. This often includes processes like burning, rusting, or reacting with other chemicals.

3. **Analyzing the Options**:
- **Option A: Evaporation of Petrol**:
- Evaporation is a physical change as it involves the change of state from liquid to gas without changing the chemical composition of petrol.

- **Option B: Burning of Liquefied Petroleum Gas (LPG)**:
- Burning is a chemical change because it produces new substances (carbon dioxide and water) and involves a change in chemical composition.

- **Option C: Heating of an Iron Rod to Red Hot**:
- Heating an iron rod is a physical change. The iron changes temperature and may change color, but its chemical composition remains the same.

- **Option D: Sublimation of Solid Ammonium Chloride**:
- Sublimation (the transition from solid to gas) is also a physical change, as the chemical composition of ammonium chloride does not change.

4. **Conclusion**:
- Among the options analyzed, the **burning of liquefied petroleum gas (Option B)** is not a physical change; it is a chemical change.

### Final Answer:
**The option that is not a physical change is: Burning of liquefied petroleum gas (LPG).**

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