Incomplete combustion of petrol or diesel oil in automobile engines can be best detects by testing the fuel gases for the presence of

Options

A. CO and `H_(2)O` vapours
B. CO and `NO_(2)`
C. CO
D. `SO_(2)`

Answer

To determine the best way to detect incomplete combustion of petrol or diesel oil in automobile engines, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Combustion**:
- Combustion is a chemical reaction where a fuel reacts with oxygen to produce energy, carbon dioxide (CO2), and water (H2O) if it is complete.

2. **Complete vs. Incomplete Combustion**:
- **Complete Combustion**: Occurs when there is enough oxygen, resulting in carbon dioxide (CO2) as the primary product.
- **Incomplete Combustion**: Happens when there is insufficient oxygen, leading to the formation of carbon monoxide (CO) along with other possible products.

3. **Identifying the Products**:
- In the case of petrol or diesel, when there is incomplete combustion, carbon monoxide (CO) is produced. This is a key indicator of incomplete combustion.

4. **Testing for Incomplete Combustion**:
- To detect incomplete combustion in automobile engines, we can test the exhaust gases for the presence of carbon monoxide (CO). The presence of CO indicates that not all the fuel has been burned completely.

5. **Conclusion**:
- The best way to detect incomplete combustion of petrol or diesel oil in automobile engines is by testing the fuel gases for the presence of carbon monoxide (CO).

### Final Answer:
The presence of carbon monoxide (CO) in the exhaust gases indicates incomplete combustion of petrol or diesel oil in automobile engines.

---