, as the charge increases on cation covalent character increases and ionic character decreases.
Polarisability of halide ions increases in the order . Polarisability is directly proportional to the size of the anion.
Higher is the charge density, higher is the polarizing power. Charge density is the ratio of charge to size.
Covalent character Covalent character increases with anion size increase.

──────────────────────────────────────────────────────────────────────────────────────────