Answer:
CH3CH2COO^-
Explanation:
CH3CH2COOH + B^- -----------> CH3CH2COO^- + BH
When a strong base reacts with propanoic acid, the only replaceable hydrogen atom in the compound is removed. Recall that carboxylic acids are often monobasic, hence the removal of that hydrogen creates a carboxylate ion whose structure has been shown in the answer section.