What is biogas ? How is it obtained ?

Explanation

### Step-by-Step Solution:

1. **Definition of Biogas**:
- Biogas is defined as a mixture of gases that primarily consists of methane (CH4), carbon dioxide (CO2), hydrogen (H2), and hydrogen sulfide (H2S).

2. **Composition of Biogas**:
- The major component of biogas is methane, which is a potent energy source. The other gases present in smaller amounts include carbon dioxide, hydrogen, and hydrogen sulfide.

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