JEE Main · 2022 · 29 Jun 2022 · Shift 1 · Chemical Bonding and Molecular Structure

According to Fajans' rules, covalent character increases with:

• Smaller cation size (higher polarizing power)
• Larger anion size (higher polarizability)

All compounds have the same anion (${\mathrm{Cl}}^{-}$), so we compare cation sizes. In Group 1, ionic radius increases down the group: ${\mathrm{Li}}^{+}<{\mathrm{Na}}^{+}<{\mathrm{K}}^{+}<{\mathrm{Cs}}^{+}$.

Smaller cations have higher charge density and greater polarizing power, leading to more covalent character.

Therefore: $\mathrm{LiCl}>\mathrm{NaCl}>\mathrm{KCl}>\mathrm{CsCl}$

Answer: (C)