When coal burns in air then

Options

A. Carbon dioxide is formed
B. Sulphur dioxide is formed
C. Carbon monoxide is formed
D. Hydrogen gas is formed

Answer

### Step-by-Step Solution:

1. **Understanding Coal Composition**: Coal primarily consists of carbon. When coal is burned, the carbon present in it reacts with oxygen from the air.

**Hint**: Remember that the main element in coal is carbon.

2. **Combustion Process**: When carbon burns in the presence of oxygen (from the air), it undergoes a chemical reaction. This reaction is known as combustion.

**Hint**: Think about what happens when a substance reacts with oxygen.

3. **Types of Combustion**: There are two types of combustion: complete and incomplete.
- **Complete combustion** occurs when there is a sufficient supply of oxygen, resulting in the formation of carbon dioxide (CO₂).
- **Incomplete combustion** occurs when there is a limited supply of oxygen, leading to the formation of carbon monoxide (CO).

**Hint**: Consider the amount of oxygen available during the burning process.

4. **Determining the Type of Combustion**: In this case, since coal is burning in air (which contains a good amount of oxygen), we can assume that there is enough oxygen for complete combustion.

**Hint**: Think about what "air" means in terms of oxygen content.

5. **Final Products**: Therefore, when coal burns in air, the primary product formed is carbon dioxide (CO₂). In scenarios where there is insufficient oxygen, carbon monoxide (CO) could be produced, but that is not the case here.

**Hint**: Recall the products formed during combustion based on the availability of oxygen.

### Conclusion:
When coal burns in air, it primarily produces carbon dioxide (CO₂) due to complete combustion.