question_answer 1)

  Assertion (A) : Though the central atom of both \[N{{H}_{3}}\] and \[{{H}_{2}}O\]molecules are \[s{{p}^{3}}\] -hybridised. Yet H-N-H bond angle is greater than that of H-O-H. Reason (R) : This is because nitrogen atom has one lone pair and oxygen atom has two lone pairs.

Answer:

  (a)  \[{{H}_{2}}O\]has two lone pairs while \[N{{H}_{3}}\] has single lone pair hence \[{{H}_{2}}O\] involves greater lone pair-bond pair repulsion.