Which of the following is not a Physical change ?

Options

A. Dissolving of oxygen in water
B. Dissolving of Carbon dioxide in water
C. Dissolving of salt in water
D. None of the above

Answer

To solve the question "Which of the following is not a Physical change?", we will analyze the options provided (though they are not listed in the question, we will assume common examples).

### Step-by-Step Solution:

1. **Understanding Physical Change**:
A physical change is a change that affects one or more physical properties of a substance. Examples include changes in state (like melting or freezing), dissolving, and changes in shape or size. Importantly, physical changes do not alter the chemical composition of the substance.

**Hint**: Remember that in a physical change, the substance retains its original properties and composition.

2. **Analyzing the Options**:
Let's consider some common examples:
- Dissolving salt in water
- Melting ice
- Burning wood
- Boiling water

**Hint**: Look for changes that involve a transformation in the chemical structure of the substance.

3. **Identifying Physical vs. Chemical Changes**:
- **Dissolving salt in water**: This is a physical change because the salt can be recovered by evaporating the water.
- **Melting ice**: This is also a physical change as the ice changes from solid to liquid but remains water.
- **Burning wood**: This is a chemical change because it produces new substances (ash, smoke, gases) and alters the chemical composition of the wood.
- **Boiling water**: This is a physical change since it involves a change in state from liquid to gas but retains the chemical composition of water.

**Hint**: Focus on whether the original substance can be recovered after the change.

4. **Conclusion**:
From the analysis, the option that is not a physical change is **burning wood**, as it results in new substances being formed.

**Final Answer**: Burning wood is not a physical change.