Question

$P{H}_3$ has lower boiling point than $N{H}_3$. Why?

Answer 1

Hydrogen bonding is obtained when H atom is attached to electronegative N,O or F atom.

$PH{}_3$ has lower boiling point than $NH{}_3$. In $NH{}_3$, intermolecular hydrogen bonding leads to molecular association. Huge amount of energy is required to break these hydrogen bonds. Hence, $NH{}_3$ has high boiling point. In $PH{}_3$, no hydrogen bonding is possible.

Therefore, $PH{}_3$ has lower boiling point.