Which of the following aqueous solution of salt have pH < 7 at 298 K?

Step-by-step solution

KNO ₃ is a salt of a strong acid ( HNO ₃ ) and a strong base ( KOH ). Its aqueous solution does not undergo hydrolysis and remains neutral with pH = 7 . Na ₂ CO ₃ is a salt of a weak acid ( H ₂ CO ₃ ) and a strong base ( NaOH ). It undergoes anionic hydrolysis, making the solution basic with pH > 7 . CH ₃ COONH ₄ is a salt of a weak acid ( CH ₃ COOH ) and a weak base ( NH ₄ OH ). Since K_a K_b , its aqueous solution is almost neutral with pH 7 . CuCl ₂ is a salt of a strong acid ( HCl ) and a weak base ( Cu(OH) ₂ )