Correct Option
The correct option isIt is a cleaner fuel that produces fewer pollutants.
Explanation
Compressed Natural Gas (CNG) is primarily composed of Methane ($CH_4$) compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is widely adopted as an alternative to conventional liquid fossil fuels like petrol and diesel due to its chemical properties that result in more efficient and cleaner combustion.
Option-wise Analysis
- It is available in liquid form which is easy to store. is Incorrect: CNG is stored in a gaseous state under high pressure (typically 200–250 bar) in cylinders, not in liquid form. Natural gas stored in liquid form is known as Liquefied Natural Gas (LNG), which requires cryogenic temperatures.
- It is a cleaner fuel that produces fewer pollutants. is Correct: The primary environmental advantage of CNG is that it burns more completely than petrol or diesel. Consequently, it emits significantly lower quantities of harmful pollutants such as carbon monoxide (CO), unburnt hydrocarbons, particulate matter (PM), and nitrogen oxides (NOx). It also produces no residue (soot) upon combustion.
- It has a higher calorific value than petrol. is Incorrect in this context: While CNG does have a higher calorific value by mass compared to petrol, this is an energy efficiency characteristic rather than a direct environmental advantage. The question specifically demands the environmental benefit, which is the reduction in pollution.
- It can be transported via pipelines. is Incorrect: While natural gas can be transported via pipelines, this is a logistical or economic advantage regarding distribution. It does not describe the environmental advantage of using the fuel within the vehicle itself.
Key Takeaway
CNG (Compressed Natural Gas) is considered a "green fuel" because its combustion releases significantly fewer toxic gases and particulate matter compared to liquid fossil fuels, thereby reducing air pollution.