Give full form of LPG and CNG.

- Hint: LPG and CNG are fuels. One of these two gases is very commonly used in the kitchen. Another one is used in vehicles.

Complete step-by-step solution -

LPG and CNG stands for Liquefied Petroleum Gas and Compressed Natural Gas, respectively.
LPG is generally obtained by extracting wet natural gas from reservoir or refining petroleum. It is mainly composed of propane - \[{{C}_{3}}{{H}_{8}}\] and butane - \[{{C}_{4}}{{H}_{10}}\]. It is widely used in kitchens as LPG cylinders and pipelines. It is also used for central heating, water heating in homes. LPG is much heavier than air.
CNG is a gaseous fuel obtained from methane wells, coal wells and natural gas wells, etc. It is mainly composed of methane - \[C{{H}_{4}}\]. CNG is methane stored at high pressure (20-25 MPa). It is used as a fuel in locomotives, automobiles and as an aerosol in rockets, as it disperses rapidly into air.

Additional Information:
When comparing LPG and CNG, we can say that LPG is more efficient as a fuel. It is because LPG has a higher calorific value than CNG. The calorific value of LPG is around 90-95 \[MJ/{{m}^{3}}\], whereas the calorific value of CNG is around 35-40 \[MJ/{{m}^{3}}\].

Note: Both LPG and CNG are clean fuels, which leave a smaller number of residues. It replaces chlorofluorocarbons as a fuel, which is a greenhouse gas and is responsible for depleting the ozone layer. Recently, LPG has also been used as an aerosol propellant in rockets.