Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases Gases : H₂ He O₂ N₂ Critical temp. (in Kelvin) 33.3 5.3 154.3 126 From the above data what would be the order of liquefaction of these gases ? Start writing the order from the gas liquefying first?

Critical temperature of a gas is the temperature at which the gas starts to liquefy or the temperature above which gas cannot be liquefied. It signifies the intermolecular forces of attraction between the gas particles. Critical temperature C T is directly related to the van der Waals constant ‘a’ .it is a measure of extent of van der waals forces of attraction between the molecules. Thus larger the ‘a’ greater is the critical temperature and eases the liquefaction of gas. C 8 T 27Rb a Here, oxygen has the higher value of critical temperature 154.3K followed by 2 N 126K , hydrogen