## Chemistry and Chemical Reactivity (9th Edition)

(a) Strongest : $HF$, Weakest: $HP{O_4}^{2-}$ (b) $F^-$ (c) $HF$ (d) $HP{O_4}^{2-}$
(a) - The strongest acid is the one with the highest $Ka$ value, and the weakest is the one with the lowest $Ka$ value. (b) - $F^-$ is the result of taking a proton from $HF$, therefore, $F^-$ is the conjugate base of this acid. (c) - The stronger the acid, the weaker is the conjugate base, therefore, $HF$, which is the strongest acid, has the weakest conjugate base. (d) - The weaker the acid, the stronger is the conjugate base, therefore, $HP{O_4}^{2-}$, which is the weakest acid, has the strongest conjugate base.