Which of the following compounds is NOT a strong base?

Ammonia (NH3) is a weak base, which means it does not dissociate completely in solution to produce hydroxide ions. Instead, when ammonia is dissolved in water, it establishes an equilibrium with its ions, where only a fraction of the ammonia molecules react with water to form hydroxide ions (OH-) and ammonium ions (NH4+). This is different from strong bases, which fully dissociate in an aqueous solution to yield a large concentration of hydroxide ions.

On the other hand, the other compounds listed are strong bases. Lithium hydroxide (LiOH), barium hydroxide (Ba(OH)2), and potassium hydroxide (KOH) completely dissociate in water, leading to significant concentrations of OH- ions, making them classified as strong bases. Understanding the distinction between strong and weak bases is important for predicting the behavior of compounds in solution and their roles in acid-base reactions.