The main constituent of Biogas and CNG is :

Question

Accepted Answer

Biogas and Compressed Natural Gas (CNG) are both primarily composed of methane, which is why Option 3 is the correct answer.

1. **Explanation for Option 3 (Methane):**
   - Methane (CH₄) is the simplest hydrocarbon and is the main component of both biogas and CNG. In biogas, methane is produced through the anaerobic digestion of organic matter by microorganisms. Typically, biogas contains about 50-75% methane. CNG, on the other hand, is composed of over 90% methane, making it an efficient and clean-burning fuel. Methane's high energy content and clean combustion make it ideal for use as a fuel in both biogas and CNG applications.

2. **Why the other options are incorrect:**
   - **Option 1 (Propane):** Propane (C₃H₈) is a hydrocarbon that is a component of liquefied petroleum gas (LPG), not biogas or CNG. While propane is used as a fuel, it is not the main constituent of biogas or CNG.
   - **Option 2 (Hydrogen Sulphide):** Hydrogen sulphide (H₂S) is a gas that can be present in biogas as an impurity, but it is not a main constituent. In fact, hydrogen sulphide is often removed from biogas to prevent corrosion and pollution. It is not present in CNG.
   - **Option 4 (Ethane):** Ethane (C₂H₆) is another hydrocarbon that can be found in natural gas, but it is not the primary component. In CNG, ethane is present in much smaller quantities compared to methane. It is not a significant component of biogas.

In conclusion, methane is the primary and most significant component of both biogas and CNG, which is why Option 3 is the correct answer.