There are three forms of matter; solid, liquid and gas. Gas is formed of the particles which have indefinite shape and have high kinetic energy. There are various examples of gases like carbon dioxide, oxygen, hydrogen, nitrogen etc. Different gases are used in different ways like we use oxygen for breathing, and plants use carbon dioxide for making food. Most of the halogens are found in gaseous form. Our atmosphere has a number of gases in it. Furthermore, natural gas is another example of gas which is widely used in our industries.