Phosphorus trichloride (PCl3) hydrolyses more easily than Nitrogen trichloride (NCl3)
Nitrogen is more electro negative than phosphorus. In NCl3, the electro negativity difference in between nitrogen & chlorine is very negligible. So, no polarity is created in NCl3 molecule’s N-Cl bond.
In case of PCl3, electro negativity of chlorine is more than phosphorus. So. Cl attracts electron towards itself from P-Cl bond. For that reason, polarity is found in P-Cl bond of PCl3.
Again we know that water is a polar compound. So, the poles of P-Cl bond of PCl3 molecule are attracted by the opposite poles of H-O-H bond of H2O molecule (Clδ- attracts Hδ- & Pδ- attracts Oδ-). As a result PCl3 is hydrolyzed easily.
On the other hand, NCl3 not being a polar compound is hydrolyzed slowly.