`NH_(3)` has higher boiling point than `PH_(3)`. Give reason.

Explanation

Due the presence of a lone pair of electrons on N and P, both `NH_(3) and PH_(3)` act as Lewis bases and accept a proton to form an additional N-H and P-H bonds respectively

However, due to smaller size of N over P, N-H bond thus formed is much stronger than the P-H bond. Therefore, `NH_(3)` has higher proton affinity than `PH_(3)`. In other words, `NH_(3)` is more basic than `PH_(3)`.