Biogas contains -

Options

A. `CO_2`
B. `H_2S`
C. `CH_4`
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding Biogas**: Biogas is a type of renewable energy source produced from the breakdown of organic matter, such as agricultural waste, manure, and food waste, through a process called anaerobic digestion.

2. **Anaerobic Digestion Process**: During anaerobic digestion, microorganisms (anaerobic decomposers) break down the organic material in the absence of oxygen. This process is crucial for the production of biogas.

3. **Microorganisms Involved**: The primary microorganisms involved in this process are methanogens, which are a type of anaerobic bacteria. They play a significant role in converting the organic material into biogas.

4. **Components of Biogas**: The main components of biogas include:
- **Methane (CH4)**: This is the primary component of biogas and is responsible for its energy content.
- **Carbon Dioxide (CO2)**: This is another significant component of biogas.
- **Hydrogen (H2)**: Although present in smaller amounts, hydrogen is also found in biogas.

5. **Conclusion**: Therefore, biogas contains a mixture of gases, primarily methane, along with carbon dioxide and hydrogen. The correct answer to the question "Biogas contains -" is "all of these" (CO2, H2, CH4).

**Final Answer**: Biogas contains CO2, H2, CH4 - all of these.

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