Mark the correct option (w.r.t. composition of biogas)

Options

A. `50-70% H_(2)`
B. `30-40% CO_(2)`
C. `95% CH_(4)`
D. `10%CO`

Answer

### Step-by-Step Solution:

1. **Understanding Biogas Composition**: Biogas is a mixture of gases produced by the anaerobic breakdown of organic matter. The primary components of biogas are methane and carbon dioxide, along with small amounts of other gases.

2. **Identifying Main Components**: The main components of biogas include:
- Methane (CH₄): Typically constitutes about 50% to 75% of biogas.
- Carbon Dioxide (CO₂): Usually makes up about 20% to 40% of biogas.
- Trace amounts of Hydrogen (H₂) and Hydrogen Sulfide (H₂S).

3. **Analyzing the Options**:
- **Option 1**: 50 to 70% of hydrogen - This is incorrect because hydrogen is present in trace amounts, not in significant percentages.
- **Option 2**: 30 to 40% of CO₂ - This is a plausible option as CO₂ can be around 20% to 40%.
- **Option 3**: 95% of methane - This is incorrect because methane is typically 50% to 75%, not 95%.
- **Option 4**: 10% of carbon monoxide - This is also incorrect as carbon monoxide is not a significant component of biogas.

4. **Conclusion**: Based on the analysis, the correct answer regarding the composition of biogas is **30 to 40% of CO₂**.