The presence of carbon monoxide(CO) in fuel gas means:

Options

A. high excess air
B. poor combustion
C. high thermal efficiency
D. all of the above

Explanation

**Step-by-Step Solution:**

1. **Understanding Carbon Monoxide (CO):**
- Carbon monoxide is a colorless, odorless gas that is produced during the incomplete combustion of carbon-containing fuels.

2. **Formation of Carbon Monoxide:**
- Carbon monoxide forms when there is not enough oxygen present for complete combustion. For example, when carbon (from fuels like coal or gasoline) burns in limited oxygen, it produces carbon monoxide instead of carbon dioxide (CO2).

3. **Incomplete Combustion:**
- The presence of carbon monoxide in fuel gas indicates that the combustion process is incomplete. This means that the fuel is not burning efficiently, and not all the carbon is being converted to carbon dioxide.

4. **Tendency of Carbon Monoxide:**
- Carbon monoxide has a tendency to react with oxygen to form carbon dioxide. This means that if there is additional oxygen available, carbon monoxide can further combust to produce carbon dioxide.

5. **Implications for Fuel Gas:**
- The presence of carbon monoxide in fuel gas suggests that the fuel gas is not burning completely. This can lead to inefficiencies in energy production and can also pose safety hazards, as carbon monoxide is toxic.

6. **Conclusion:**
- Therefore, the presence of carbon monoxide in fuel gas means that there is incomplete combustion occurring, which can lead to reduced efficiency and potential dangers.

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