Biogas contains

Options

A. `30-40% ` methane
B. `50-70% CO_(2)`
C. `50-70% `methane
D. `20%` methane

Answer

### Step-by-Step Solution:

1. **Understanding Biogas Composition**:
- Biogas is primarily composed of two main gases: methane (CH4) and carbon dioxide (CO2).

2. **Identifying Methane Content**:
- The methane content in biogas typically varies. It is important to note the range of methane concentration in biogas.

3. **Methane Percentage in Biogas**:
- Research and studies indicate that the methane content in biogas can range from 50% to 70%. This is a significant proportion of the total gas composition.

4. **Identifying Carbon Dioxide Content**:
- The remaining portion of biogas, after accounting for methane, is mainly carbon dioxide along with small amounts of water vapor and other gases.

5. **Conclusion**:
- Based on the information gathered, we can conclude that the correct answer to the question "Biogas contains" is that it contains 50 to 70% methane.

6. **Final Answer**:
- Therefore, the correct option is **C: 50 to 70% methane**.