Consider the following substances :
1. `OF_(2)` 2. `Cl_(2)O` 3. `Br_(2)O`
The correct sequence X - O - X bond angle is

Options

A. `1gt 2 gt 3`
B. `2 gt 1 gt 3`
C. `1 gt 3 gt 2`
D. `3 gt 2 gt `

Answer

D

Explanation

Bond angles are distorted on account of the lone pairs. The bonding electrons in `OF_(2)` are nearer the F atom, because of its higher electronegativity. Hence, the repusion between the lone pairs exceeds that between the bonded peirs Consequently, then F-O-F bond angle is less than the tetrahedral angle of `109^(@) 28'`. In `Cl_(2)O`, the bonding pairs of electrons are closer to oxygen, because of its greater electronegativity. Hence, in this case also repulsion between the bonded pair of electrons exceeds that between then Ione pairs. Hence, the bond angle is greater than `109^(@) 28'` and is found to be equal to `111^(@)`. By similar reasoning, the bond angle in is expected to be greater than `111^(@)`. In `Cl_(2)O and Br_(2)O` the bond angles are also increased, because of steric crowding of larger halogen atoms.