The correct answer for the main constituent of Gobar gas is option 2: Methane.
To better understand the options and make an informed choice, let`s analyze each one:
1. Ethane: Ethane is a hydrocarbon gas that is commonly used as a fuel and a refrigerant. However, it is not the main constituent of Gobar gas.
2. Methane: Methane is the main constituent of Gobar gas (also known as biogas). It is a colorless and odorless gas that is produced by the decomposition of organic matter (such as animal dung or plant waste) in the absence of oxygen. Methane is a potent greenhouse gas and is commonly used as a source of energy.
3. Propane: Propane is another hydrocarbon gas that is commonly used as a fuel. While it can be a component of biogas in small amounts, it is not the main constituent of Gobar gas.
4. Acetylene: Acetylene is a highly flammable gas that is used for welding and metal cutting. It is not a constituent of Gobar gas.
In summary, the main constituent of Gobar gas is Methane, making option 2 the correct answer.