Question

Out of the following gases, van der Waals' constant $a$ is maximum in:

• A. $He$
• B. $H_2$
• C. $O_2$
• D. $N{H}_3$

Answer 1

The correct option is D $N{H}_3$

$a\propto \text{Intermolecular forces of attraction}$,
Intermolecular forces in $N{H}_3$ are maximum due to hydrogen bonding while other gases are having relatively weak London or van der Waals' forces, hence its van der Waals' constant 'a' will be maximum.
Hence, the correct answer is option (d).