Which of the following is not a physical change ?

Options

A. salt is added to water
B. charcoal burns
C. ice melts
D. iron nail is magnetised

Answer

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

### Step-by-Step Solution:

1. **Understanding Physical Changes**:
- A physical change is a change that does not alter the chemical composition of a substance. In physical changes, no new substances are formed.

2. **Analyzing the Options**:
- **Option 1: Salt is added to water**:
- When salt is dissolved in water, it does not create a new substance; the salt can be recovered by evaporating the water. Thus, this is a physical change.

- **Option 2: Charcoal burns**:
- When charcoal (which is primarily carbon) burns, it reacts with oxygen to form carbon dioxide (CO2). This process results in the formation of a new substance (CO2), indicating that this is a chemical change.

- **Option 3: Ice melts**:
- Ice melting into water is a change in state from solid to liquid. No new substance is formed; therefore, this is a physical change.

- **Option 4: Iron nail is magnetized**:
- Magnetizing an iron nail does not create a new substance; it simply changes the physical property of the iron. Thus, this is also a physical change.

3. **Conclusion**:
- Among the options analyzed, the only one that is not a physical change is **charcoal burns**.

### Final Answer:
The option that is not a physical change is **charcoal burns**.