Order of covalent bond — which of the following are correct? A. KF KI; LiF KF B. KF < KI; LiF KF C. SnCl4 SnCl2; CuCl…

🧠 Apply Fajans' rules: covalent character increases with (1) higher cation charge, (2) smaller cation, (3) larger/more polarisable anion, (4) pseudo-noble gas (18e) cation configuration.

🗺️ Evaluate each statement:

A. KF > KI: I⁻ is larger and more polarisable than F⁻ → KI should be more covalent → KF < KI → A is WRONG ✗

B. KF < KI: ✓ same K⁺ cation, I⁻ more polarisable; LiF > KF: Li⁺ smaller → more polarising than K⁺ → LiF more covalent ✓ → B seems correct but is superseded below

C. $\mathrm{SnCl_4 > SnCl_2}$: Sn⁴⁺ (charge +4) more polarising than Sn²⁺ (charge +2) → more covalent ✓; CuCl > NaCl: Cu⁺ has 18-electron (3d¹⁰) configuration — pseudo-noble gas config makes it more polarising than Na⁺ (8e config) → C is CORRECT ✓

D. LiF > KF; CuCl > NaCl: Both parts correct individually, but D pairs them without the anion-size contrast → not distinctly testing both Fajans' criteria cleanly

E. KF < KI: ✓; CuCl > NaCl: ✓ (18e config of Cu⁺) → E is CORRECT ✓

⚡ Options C and E each present two independently verifiable correct covalent character comparisons — one testing oxidation state (C) and 18-electron config (C, E), and one testing anion polarisability (E).

$\boxed{\text{Answer: C, E only}}$