Which among the following compounds is the main constituent of natural gas?

1. A

   Butane

   Option (a) claims butane is the main constituent of natural gas. Butane is primarily found in liquefied petroleum gas rather than natural gas. Therefore, this option is incorrect.

2. B

   Hexane

   Option (b) claims hexane is the main constituent of natural gas. Hexane is a liquid alkane commonly used as a solvent in various industrial processes. Thus, it is not the principal component of natural gas.

3. C

   Benzene

   Option (c) claims benzene is the main constituent of natural gas. Benzene is an aromatic hydrocarbon derived from petroleum refining rather than being the primary component of natural gas. Hence, this choice is wrong.

4. D

   Methane

   Option (d) claims methane is the main constituent of natural gas. Natural gas is predominantly composed of methane, typically making up over seventy to ninety percent of its total volume, serving as the cleanest burning fossil fuel among all hydrocarbons. Therefore, this option is the correct official key for the question.

Summary. Official key is (d) Methane. Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, along with varying amounts of heavier alkanes and sometimes a small percentage of carbon dioxide, nitrogen, or hydrogen sulfide. While other hydrocarbons like butane and propane are present in smaller quantities or extracted separately, methane remains the principal constituent by a wide margin. Confusion often arises with LPG, which consists mainly of butane and propane. This makes option (d) the correct and comprehensive answer.