Assertion: Charcoal does not produce any smoke.
Reason: Charcoal contains only carbon.

Answer

To analyze the given assertion and reason, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Charcoal does not produce any smoke."
- This means that when charcoal is burned, it does not release visible particles or gases that we typically associate with smoke.

2. **Understanding the Reason**:
- The reason provided is that "Charcoal contains only carbon."
- This implies that the chemical composition of charcoal is purely carbon, which affects how it burns.

3. **Combustion Process**:
- When a substance burns, it undergoes a chemical reaction with oxygen, known as combustion.
- There are two types of combustion: complete and incomplete.
- Complete combustion occurs when there is enough oxygen, resulting in carbon burning to form carbon dioxide (CO2) without producing smoke.
- Incomplete combustion occurs when there is insufficient oxygen, leading to the formation of carbon monoxide (CO) and other particles, which produce smoke.

4. **Analyzing Charcoal's Combustion**:
- Since charcoal is composed mainly of carbon, when it burns in sufficient oxygen, it undergoes complete combustion.
- This complete combustion of charcoal results in the production of CO2 gas, which is colorless and does not produce smoke.

5. **Conclusion**:
- The assertion that charcoal does not produce smoke is correct because it burns completely.
- The reason that charcoal contains only carbon is also correct, and it explains why charcoal does not produce smoke during combustion.
- Therefore, both the assertion and the reason are true, and the reason is the correct explanation for the assertion.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.