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

Let's break down the question step by step:

### (i) Why is `PCl_(5)` more covalent than `PCl_(3)`?

1. **Identify the oxidation states**: In `PCl_(5)`, phosphorus has an oxidation state of +5, while in `PCl_(3)`, it has an oxidation state of +3.

2. **Apply Fajans' Rule**: Fajans' rule states that the covalent character of a compound increases with the increase in the oxidation state of the cation. This is because a higher oxidation state leads to a smaller cation size, which can polarize the electron cloud of the anion more effectively.

...