For real gases the relation between p, V and T is given by c=van der Waal's equation
`(p+ (an^(2))/V^(2)) (V-nb)=nRT`
where, 'a' and 'b' are van der Waal's constanrs, 'nb' is approximately equal to the total volume of the molecules of a gas. 'a' is the measure of magnitude of intermolecular attraction.
(i) Arrange the following gases in the increasin order of 'b'. give reason.
`O_(2), CO_(2), H_(2), He`
(ii) Arrange the following gases in the decreasing order of magnitude of 'a'. Give reason.
`CH_(4), O_(2), H_(2)`

Explanation

(i) `H_(2)ltHe ltO_(2)ltCO_(2)`. This is because of increase in size.
(ii) `CH_(4)gt O_(2) gt H_(2)`. This is because intermolecular forces are the highest in `CH_(4)` and the lowest in `H_(2)` because intermolecular forces increases with increase in number of electrons in a molecule.