Question

According to Hard–Soft Acid–Base (HSAB) principle, the CORRECT option(s) for the solubility trend in water is/are

• A. AgF > AgCl > AgBr > AgI
• B. LiBr > LiCl > LiF
• C. AgF < AgCl < AgBr < AgI
• D. LiBr < LiCl < LiF

Hint:

Use HSAB for {relative lattice strength}: soft–soft pairs bind more strongly (lower solubility); hard–soft pairs bind weakly (higher solubility). For Li$^+$ halides, LiF is characteristically the least soluble.

Answer 1

The Correct Option is A, B

Idea (HSAB). Ag$^+$ is a soft acid; among halides, F$^-$ is hard and I$^-$ is soft. Soft–soft (AgI) interactions are strongest $⇒$ lowest solubility in water, while mismatched hard–soft (AgF) is weakest $⇒$ highest solubility. Hence for AgX: AgF > AgCl > AgBr > AgI \,$⇒$\, (A) is correct.
For Li$^+$ (a hard small cation), hydration favors larger, more polarizable anions less strongly than the lattice-energy increase for small F$^-$. Net result: solubility of LiX increases with halide size: LiF (least) < LiCl < LiBr (most). Thus (B) is correct, while (C) and (D) are the reverse of the true trends.