`PH_(3)` has lower boiling point that `NH_(3)`. Why ?

Explanation

The electronegativity of N(3.0) is much higher than that of P(2.1). Therefore, `NH_(3)` undergoes extensive intermolecular H-bonding and hence it exists as an associated molecule. To break these H-bonds, a large amount of energy is needed. On the other hand, `PH_(3)` does not undergo H-bonding and thus exist as discrete molecules. Therefore, the boiling point of `PH_(3)` is much lower than that of `NH_(3)`.