Question

Assertion- $NC{l_3}$ undergoes hydrolysis.
Reason- Chlorine possesses vacant d-orbitals.

Answer 1

In order to answer this question, to know whether the given reason is correct or not for the given Assertion, first we should do hydrolysis of $NC{l_3}$ and try to understand the reason of hydrolysis of $NC{l_3}$.

Complete step-by-step answer:
Both Assertion and Reason are correct and Reason is the correct explanation for the Assertion.
Chlorine contains vacant $d - orbitals$ in its outermost shell. When $Cl$ is an excited state, it forms bonds with water molecules. If we put $NC{l_3}$ in water, it undergoes hydrolysis.

The nitrogen in $NC{l_3}$ is often considered to have the 3 oxidation state and the chlorine atoms are considered to be in the $+ 1$ oxidation state.
It is hydrolysed by hot water to release ammonia and hypochlorous acid.
$NC{l_3} + 3{H_2}O \to N{H_3} + 3HOCl$

Nitrogen can combine with three chlorine atoms, forming nitrogen trichloride, or $NC{l_3}$ . Nitrogen shares its electrons with the chlorine atoms, so all of the atoms have their shells filled. The $N - Cl$ bonds are therefore largely unpolarised and attack on the nitrogen by the oxygen atoms of water is therefore not favoured.

Note: In $NC{l_3}$ , nitrogen and chlorine have similar electro-negativities resulting in non-polar bonds. Nitrogen doesn’t have empty d-orbitals so the hydrolysis takes place with the donation of lone pair of the electron by nitrogen to the hydrogen atom of water.