What suffix is used in the nomenclature of carboxylic acids?

The suffix used in the nomenclature of carboxylic acids is "-oic acid." This suffix indicates the presence of the carboxyl functional group (-COOH) in the compound. When naming a carboxylic acid, the longest carbon chain containing the carboxylic group is identified, and the name of the alkane corresponding to that chain is modified to include "-oic acid." For example, a carboxylic acid derived from a three-carbon alkane (propane) is called propanoic acid.

The other suffixes listed do not correctly denote carboxylic acids. The suffix "-ol" is used for alcohols, which contain a hydroxyl group (-OH) instead. "-oate" is seen in the nomenclature of esters, indicating a different functional group formed from a carboxylic acid and an alcohol. The term "-acetic" is specific to acetic acid but does not serve as a general suffix for all carboxylic acids. Thus, "-oic acid" is the standard suffix used when naming these types of compounds.