For real gas van der Waals equation is written as `(p + (an^2)/(V^2)) (V-nb)=nRT` where a and b are van der waals constants . Two sets of gases are
`O_(2),CO_(2) H_(2) ` and He
`CH_(4), O_(2) and H_(2)`
The gaeses given in set- in increasing order of b and gaes given in set -II in decreasing order of a are arranged below. Select the correct order from the following :

Options

A. (I) `He lt H_(2) lt CO_(2) lt O_(2)` , (II) `CH_(4) gt H_(2) gt O_(2)`
B. (I) `O_(2) lt He lt H_(2) lt CO_(2)` , (II) `H_(2) gt O_(2) gt CH_(4)`
C. (I) `H_(2) lt He lt O_(2) lt CO_(2)` , (II) `CH_(4) gt O_(2) gt H_(2)`
D. (I) `H_(2) lt O_(2) lt He lt CO_(2)` , (II) `O_(2) gt CH_(4) gt H_(2)`.

Answer

C

Explanation

van der Waals constant 'a' reprsents intermolecular forces of attraction in the gaseous molecules. The increasing order of attractive force in set (I) is :
`H_(2) lt He lt O_(2) lt CO_(2)`
van der Waals' constant 'b' represents molecular size or molecular volume. The decreasing order of molecular volume is :
`:.` (c ) is the correct order.