Ideal gas :
(i) Ideal gas completely follows the laws of Boyle's, Charles's and pressure in every condition of temperature, pressure and volume.
(ii) If coefficient of pressure expansion and coefficients of volume expansions are equal to each other and it value is 1/273.
(iii) No force of attraction or repulsion acts between its molecules.
(iv) Its molecules are very small.
(v) Ideal gas cannot be changed into solid or liquid state because attraction between molecules is necessary in liquid and solid states.
(vi) The gas which follows the assumptions of dynamic theory is called ideal gas.
(vii) Generally monoatomic gases are ideal gases. Hydrogen, nitrogen, oxygen and helium gases are ideal gases. It is believed that because all of them are liquid with difficulty.