Assertion (A): Addition of sodium chloride to an aqueous solution of acetic acid suppresses the dissociation of the acid. Reason (R): The presence of a common chloride ion shifts the ionic equilibrium backward according to Le Chatelier principle.

💡 Solution & Explanation

The assertion is false because sodium chloride does not suppress the dissociation of acetic acid since neither sodium nor chloride ions are common ions in acetic acid solution; the common ion effect for acetic acid requires acetate or hydrogen ions. However, the reason correctly states the general principle of Le Chatelier and the common ion effect where adding a common ion suppresses weak electrolyte dissociation. Understanding ionic equilibria is crucial for buffer solution preparation in analytical chemistry.