A salt is formed from the reaction of an acid and a base. The nature of the salt solution (acidic, basic, or neutral) depends on the strengths of the parent acid and base. - Salt of strong acid + strong base: Neutral solution (e.g., NaCl from HCl and NaOH). - Salt of strong acid + weak base: Acidic solution (e.g., NH₄Cl from HCl and NH₄OH). The cation of the weak base undergoes hydrolysis. - Salt of weak acid + strong base: Basic solution (e.g., NaCN from HCN and NaOH). The anion of the weak acid undergoes hydrolysis. - Salt of weak acid + weak base: Solution acidity/basicity depends on the relative strengths (Ka vs Kb) of the parent acid and base (e.g., CH₃COONH₄ from CH₃COOH and NH₄OH).Let's analyze the options: A) NH₄Cl: Formed from NH₄OH (weak base) and HCl (strong acid). Salt of weak base and strong acid. B) CH₃COONH₄: Formed from CH₃COOH (weak acid) and NH₄OH (weak base). Salt of weak acid and weak base. C) NaCN: Formed from HCN (weak acid) and NaOH (strong base). Salt of weak acid and strong base. D) NaCl: Formed from HCl (strong acid) and NaOH (strong base). Salt of strong acid and strong base.