Which of the following is not a physical change?

Options

A. Boiling of water to give water vapour
B. Melting of ice to give water
C. Dissolution of salt in water
D. Combustion of liquified petroleum gas (LPG)

Explanation

To determine which of the following options is not a physical change, we need to analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Physical and Chemical Changes**:
- A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include changes in state (like melting, freezing, boiling) and dissolving.
- A chemical change, on the other hand, involves a transformation that alters the chemical composition of a substance, resulting in the formation of new substances.

2. **Analyzing the First Option: Boiling of Water**:
- When water is boiled, it changes from liquid to vapor (gas). This is a change in state but does not change the chemical composition of water (H2O).
- Therefore, boiling of water is a **physical change**.

3. **Analyzing the Second Option: Dissolution of Salt in Water**:
- When salt (NaCl) is dissolved in water, it separates into its ions but remains chemically the same. If the water is evaporated, the salt can be recovered unchanged.
- Thus, this process is also a **physical change**.

4. **Analyzing the Third Option: Combustion of Liquefied Petroleum Gas (LPG)**:
- Combustion is a chemical reaction where LPG (a hydrocarbon) reacts with oxygen to produce carbon dioxide (CO2) and water (H2O). This process results in new substances being formed.
- Therefore, combustion of LPG is a **chemical change**.

5. **Conclusion**:
- Among the options provided, the combustion of liquefied petroleum gas (LPG) is not a physical change; it is a chemical change.

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

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