Final answer:
An acidic solution will be formed when a salt has the conjugate acid of a weak base and the conjugate base of a strong acid because only the conjugate acid part of the salt will significantly react with water to increase the solution's acidity.
Step-by-step explanation:
When a salt is composed of the conjugate acid of a weak base and the conjugate base of a strong acid, the resulting solution will be acidic. This occurs because the conjugate acid of a weak base tends to release protons (H+) in water, leading to an increase in the hydronium ion concentration and thus lowering the pH of the solution.
The anion, which is the conjugate base of a strong acid, will not significantly react with water since strong acids completely dissociate in water and have very weak conjugate bases. In contrast, the salt of a weak acid and a strong base would form a basic solution because the conjugate base (anion) would react with water to produce hydroxide ions (OH-).