# Why is it that in the case of nitrogen $\text{NCl}_3$ is possible, but not $\text{NCl}_5$, while in the case of phosphorus, $\text{PCl}_3$ and $\text{PCl}_5$ are possible.
$\begin{array}{1 1} \text{Due to the lower electronegativity of P than N} \\ \text{Due to the lower tendency of H-bond formation in P than N} \\ \text{Availability of vacant d orbitals in P but not in N} \\ \text{P occurs in solid state, while N is in gaseous state at room temperature}\end{array}$