Which of the following is an example of a weak base?

Ammonia is classified as a weak base because it does not fully ionize in aqueous solution. In water, ammonia (NH₃) can accept a proton (H⁺) to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻). However, this process is an equilibrium reaction, meaning that only a portion of ammonia molecules will react to form ions. Consequently, the concentration of hydroxide ions produced in solution is relatively low compared to strong bases, which completely dissociate and produce a high concentration of hydroxide ions.

In contrast, hydrochloric acid is a strong acid that dissociates completely in water, while sodium hydroxide and potassium chloride are both strong base and neutral salt, respectively, that dissociate completely in solution. Understanding the behavior of acids and bases in terms of ionization is essential for identifying whether a substance is a weak or strong base.