On reaction with $Cl_2$,phosphorus forms two types of halides $A$ and $B$. Halide $A$ is a yellowish-white powder,while halide $B$ is a colourless oily liquid. Identify $A$ and $B$ and write the formulas of their hydrolysis products.

(A) is $PCl_5$ and $B$ is $PCl_3$.
$B (PCl_3)$ undergoes hydrolysis to form phosphorous acid $(H_3PO_3)$ and hydrogen chloride $(HCl)$:
$PCl_3 + 3 H_2O \rightarrow H_3PO_3 + 3 HCl$
$A (PCl_5)$ undergoes hydrolysis to form phosphoric acid $(H_3PO_4)$ and hydrogen chloride $(HCl)$:
$PCl_5 + 4 H_2O \rightarrow H_3PO_4 + 5 HCl$