Arrange the following in the decreasing order of covalent character:

(A) LiCl (B) NaCl (C) KCl (D) CsCl

Question

Arrange the following in the decreasing order of covalent character:

(A) LiCl (B) NaCl (C) KCl (D) CsCl

Canvas Classes · Accepted Answer

Covalent character in ionic compounds increases with Fajans' rules:
- Smaller cation → higher charge density → more polarisation → more covalent

Step 1 — Cation sizes (ionic radii):
- Li⁺: 76 pm (smallest)
- Na⁺: 102 pm
- K⁺: 138 pm
- Cs⁺: 167 pm (largest)

Step 2 — Smaller cation = more polarising power = more covalent character:

Therefore covalent character:

Answer: Option (3)

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