Final answer:
From the provided options, the anions that act as weak bases in solution are ClO₋ (hypochlorite ion) and C₃H₃O₃₋ (pyruvate ion). Chlorate ion (ClO₃₋) and chloride ion (Cl₋) are not considered weak bases in their reactions with water.
Step-by-step explanation:
The anions that act as weak bases in solution according to the Brønsted-Lowry theory are those that can accept a proton (H+) from water to form hydroxide ions (OH-) or less acidic or even neutral species.
- ClO₃₋ - Chlorate ion does not typically act as a base in solution.
- ClO₋ - Hypochlorite ion can act as a weak base in solution.
- C₃H₃O₃₋ - Pyruvate ion can act as a weak base as it can accept a proton to form a less acidic species.
- Cl₋ - Chloride ion, while it does have available lone pairs for proton acceptance, does not react significantly with water, so it is not considered a weak base in solution.
Therefore, the anions from the list that can act as weak bases are ClO₋ and C₃H₃O₃₋.