Wax is a hydrocarbon. When the wick is lit, the solid wax melts and becomes a liquid. This liquid soaks into the wick and in the heat it is vaporized. The flame is a zone of combustion of these vapours of wax. When a candle burns, the carbon from the wax combines with oxygen in the air. Carbon undergoes oxidation, and gets changed into carbon dioxide. At the same time hydrogen combines with air to form water vapours. Some of the carbon does not burn and is deposited as soot.
The formation of soot occurs when

Options

A. there is not enough oxygen for burning and few carbon particles are left unburnt
B. there is enough oxygen for burning carbon particles
C. there is not enough oxygen for burning hydrogen
D. hydrocarbon is converted to soot on heating.

Explanation

### Step-by-Step Solution:

1. **Understanding the Process of Combustion**:
- When a candle burns, the wax (a hydrocarbon) melts and vaporizes. The combustion of these vapors occurs in the presence of oxygen from the air.

2. **Identifying the Products of Combustion**:
- During combustion, carbon from the wax combines with oxygen to form carbon dioxide (CO₂), and hydrogen combines with oxygen to form water vapor (H₂O).

3. **Recognizing Incomplete Combustion**:
- Sometimes, not all carbon burns completely. This incomplete combustion occurs when there is insufficient oxygen available.

4. **Formation of Soot**:
- The unburnt carbon particles that result from incomplete combustion are deposited as soot. This happens specifically when the oxygen supply is limited.

5. **Evaluating the Options**:
- The question provides several options regarding the formation of soot.
- **Option 1**: There is not enough oxygen for burning, and few carbon particles are left unburnt. (This is correct.)
- **Option 2**: There is enough oxygen for burning carbon particles. (This is incorrect; if there is enough oxygen, all carbon would burn.)
- **Option 3**: There is not enough oxygen for burning of hydrogen. (This is incorrect; hydrogen combustion is not the issue here.)
- **Option 4**: Hydrocarbon is converted to soot on heating. (This is incorrect; soot forms due to limited oxygen, not just heating.)

6. **Conclusion**:
- The correct option is **Option 1**, which states that the formation of soot occurs when there is not enough oxygen for burning, leading to unburnt carbon particles.