Question

The bond lengths and bond angles in the molecules of methane, ammonia, and water are given below:

This variation in bond angle is a result of
(i) the increasing repulsion between H atoms as the bond length decreases
(ii) the number of nonbonding electron pairs in the molecule
(iii) a nonbonding electron pair having a greater repulsive force than a bonding electron pair
A. (i), (ii), and (iii) are correct
B. (i) and (ii) are correct
C. (ii) and (iii) are correct
D. only (i) is correct

Answer 1

Correct Answer - C
Option (i) is wrong because the smaller the bond length, the closer the H atoms are, the greater the repulsion between them and, hence, the greater the bond angle. C atom has no lone pair `(109.5^@)`. N atom has one lone pair `(107^@)`, and O atom has two lone pairs `(104.5^@)`. The more the number of lone pairs, the greater the repulsion on bond pairs and, thus, the smaller the bond angle is. Hence, options (ii) and (iii) are correct.