Question

The constant '$a$' in van der Waals' equation 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 Waal forces, hence its van der Waals constant 'a' will be maximum.
Hence, the correct answer is option (d).