Account for the following :
(i) `PCl_(5)` is more covalent than `PCl_(3)`.
(ii) Iron on reaction with HCl forms `FeCl_(2)` and not `FeCl_(3)`.
(iii) The two O-O bond lengths in the ozone molecule are equal.

Explanation

Because HCl is a mild oxidising agent/ formation of hydrogen gas prevents the formation of `FeCl_(3)` .