Name the gas which mainly contains methane, but also contains `CO_2`, `H_2 S` in small amount :

Options

A. Coal
B. Petroleum
C. Natural gas
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a gas that primarily consists of methane and also contains small amounts of carbon dioxide (CO₂) and hydrogen sulfide (H₂S).

2. **Analyzing Options**:
- **Coal**: This is a solid fossil fuel and does not exist in gaseous form. Therefore, it cannot be the answer.
- **Petroleum**: This is a liquid fossil fuel and also does not qualify as a gas. Hence, it is not the correct answer.
- **Natural Gas**: This is a gaseous fossil fuel that is primarily composed of methane (CH₄). It can also contain small amounts of carbon dioxide (CO₂) and hydrogen sulfide (H₂S).

3. **Conclusion**: Based on the analysis, the gas that mainly contains methane and also has CO₂ and H₂S in small amounts is **Natural Gas**.

**Final Answer**: Natural Gas

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