What is the molecular structure of pentanoic acid?

The molecular structure of pentanoic acid is represented as CH3(CH2)4COOH. Pentanoic acid, also known as valeric acid, has a five-carbon chain with a carboxylic acid functional group (-COOH) at one end. In this structure, the "CH3" represents the methyl group at one end, and the "(CH2)4" indicates a linear chain of four methylene groups, totaling five carbons when combined with the carboxyl group.

The other choices do not accurately depict the five-carbon chain needed for pentanoic acid. For instance, the structure in the answer provided, which specifies a four-carbon chain plus the carboxylic acid, corresponds to butanoic acid, not pentanoic acid. Additionally, the third and fourth structures lack the appropriate number of carbons to represent pentanoic acid. Since pentanoic acid has five carbon atoms, the correct structure must reflect that with the formula aligning to five total carbons including the carboxylic acid group. Thus, the proper representation of pentanoic acid is indeed CH3(CH2)4COOH.