Choose the molecules in which hybridization occurs in the ground state?

$\text{ (P) }{\mathrm{BCl}}_3$

$\text{ (Q) }{\mathrm{NH}}_3$

$\text{ (R) }{\mathrm{PCl}}_3$

$\text{ (S) }{\mathrm{BeF}}_2$

The correct answer is

The electronic configuration of ${\mathrm{PCl}}_3$ and $N{H}_3$ is given below,

${\mathrm{PCl}}_3:\mathrm{P}\to 1s^{2}2s^{2}2p^{6}3s^{2}3p^3$

${\mathrm{NH}}_3:\mathrm{N}\to 1s^{2}2s^{2}2p^3$

${\mathrm{PCl}}_3$ is a covalent compound.  By exchanging valence electrons, the chlorine atoms and phosphorus complete their octet.

Both have three electrons in the p subshell. Hence, in ${\mathrm{PCl}}_3$ and c hybridization occurs in the ground state.