Assertion (A): Though the central atom of both $N{H}_{3}and{H}_{2}O$ molecules are $s{p}^3$ hybridized, yet H–N–H bond angle is greater than that of H–O–H.
Reason (R):  $N{H}_3$ has lone pair-bond pair repulsions which are more than bond pair-bond pair repulsions where as $H_{2}O$ has lone pair-lone pair repulsions which are more than lone pair-bond pair and bond pair-bond pair repulsions