Which of the following is an example of a weak acid and its conjugate base?

The choice of acetic acid and acetate as an example of a weak acid and its conjugate base is appropriate because acetic acid (CH₃COOH) only partially dissociates in aqueous solution to produce hydrogen ions (H⁺) and acetate ions (CH₃COO⁻). This means that at any given moment, a significant concentration of undissociated acetic acid remains in the solution, characterizing it as a weak acid.

When acetic acid donates a proton, the resulting acetate ion is its conjugate base. This relationship is essential in understanding acid-base chemistry, as the strength of the acid is related to the extent of its dissociation in water: weak acids only partially dissociate, resulting in equilibrium between the undissociated acid and the ions produced.

In contrast, the other options provided involve strong acids, which fully dissociate in aqueous solutions. Hydrochloric acid, sulfuric acid, and nitric acid are all strong acids, meaning they complete the dissociation process, leading to a negligible concentration of the undissociated acid and, as a result, do not exemplify the weak acid/conjugate base dynamic represented by acetic acid and acetate.