Question

The value of van der Waal's constant '$a$' for the gases $O_2,N_2,N{H}_3$ and $C{H}_4$ are 1.360, 1.390, 4.170 and 2.253 $L^{2}atmmo{l}^{-2}$ respectively. The gas which can be most easily liquefied is:

• A. $O_2$
• B. $N_2$
• C. $N{H}_3$
• D. $C{H}_4$

Answer 1

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

Van der Waal's constant '$a$' is an indirect measure of inter-molecular attractive forces. Ammonia contains strong inter-molecular forces of attraction. Inter-molecular hydrogen bonding is absent in other gases.
Hence, the value of van der Waal's constant '$a$' is larger for ammonia than for other gases.
Hence, ammonia can be most easily liquefied.