Explain how the use of CNG in automobiles has reduced pollution in our cities.

The use of CNG in automobiles has reduced pollution in our cities as it is considered as a quality fuel because:

(a) It gives out less carbon dioxide gas, carbon monoxide gas, sulphur dioxide and nitrogen dioxide, which is beneficial as they play a crucial role in global warming and acid rain.

(b) It leaves behind no residue after its combustion.

[Extra information: CNG is compressed natural gas. CNG consists primarily of methane but also contains ethane, propane and heavier hydrocarbons. Natural gas is very important fossil fuel because it is easy to transport through pipes. It can be used as fuel in homes and factories. It is also used as a starting material for the manufacture of a number of chemicals and fertilizers. It is advantageous to use CNG as a fuel because it is less polluting than petrol. It is a clean-burning fuel. It produces 45% less hydrocarbons than petrol. The great advantage of CNG is that it can be used directly for burning in homes and factories where it can be supplied through pipes.]