Answer
(a) $CH{O_2}^-$ is a weak base.
(b) $Cl{O_4}^-$ is a pH-neutral anion.
Work Step by Step
1. Identify the conjugate acid.
(a) $HCHO_2$
(b) $HClO_4$
2. Determine if the conjugate acid is strong or weak.
(a) According to table 16.5, $HCHO_2$ is a weak acid.
(b) According to table 16.3, $HClO_4$ is a strong acid.
3. If the conjugate acid is weak, the anion is a weak base; if the conjugate acid is strong, the anion is pH-neutral.
