Question

Q:-17 Assertion (A) : Though the central atom of both NH3 and H20 molecules are sp3
hybridised, yet H-N-H bond angle is greater than that of H-0-H.
Reason (R) : This is because nitrogen atom has one lone pair and oxygen atom has
two lone pairs.
a) A and R both are correct, and Ris the correct explanation of A.
b) A and R both are correct, but R is not the correct explanation of A.
c) A is true but R is false.
d) A and R both are false.​

Answer 1

Correct option is a)A and R both are correct, and Ris the correct explanation of A .

For the same hybridised molecules, bond angle is inversely proportional to lone pair. Lone pair - lone pair repulsion is stronger in nature in comparison to lone pair - bond pair repulsion.

Oxygen atom contains two lone pairs and hence lone pair - lone pair repulsion occurs there decreasing the bond angle.

While nitrogen has only one lone pair and hence lone pair - bond pair repulsion occurs which is less strong comparatively, and hence bond angle is greater with respect to water molecule.