Le Chatelier's Principle in Silver Halide-Ammonia System

Steps:

• AgNO3 adds Ag+ to X–, forming precipitate AgX(s) via equilibrium 1 (Ksp determines solubility).
• Adding NH3 forms Ag(NH3)2+ complex via equilibrium 2, consuming free Ag+.
• Increased [NH3] shifts equilibrium 2 right, lowering [Ag+].
• By Le Chatelier's principle, equilibrium 1 shifts right to replenish Ag+, dissolving AgX(s).

Why B is correct:

• Increasing [NH3] removes Ag+ (via equilibrium 2), so equilibrium 1 shifts right per Le Chatelier's principle to restore [Ag+].

Why the others are wrong:

• A: Equilibrium 1 lies right for insoluble AgX (all halides except F–); "left" implies high solubility, incorrect for typical X–.
• C: Equilibrium 2 K depends only on Ag+ and NH3, independent of X–.
• D: Equilibrium 2 is ligand substitution/complexation, not electron transfer (no redox).

Final answer: B