The correct option is Methane.
Explanation
Compressed Natural Gas (CNG) is a fuel gas used in vehicles, primarily as a substitute for gasoline (petrol), diesel fuel, and propane/LPG. It is produced by compressing natural gas to less than 1% of the volume it occupies at standard atmospheric pressure.
Detailed Analysis:
- Methane ($CH_4$): This is the primary component of CNG, typically constituting between 80% to 90% of its composition. It is the simplest alkane and burns with a clean flame, producing fewer pollutants compared to other fossil fuels.
- Ethane, Propane, and Butane: While raw natural gas contains small amounts of heavier hydrocarbons like ethane, propane, and butane, these are often separated during processing. In the context of commercial fuels, Propane and Butane are the major constituents of Liquefied Petroleum Gas (LPG), not CNG.
Key Takeaway:
The major chemical component of CNG is Methane, whereas LPG is primarily composed of Propane and Butane.