Which one of the following is the correct chemical formula of carboxylic acid ?

Carboxylic acids are organic compounds characterized by the presence of the carboxyl functional group (-COOH) [1]. The general formula for a saturated aliphatic carboxylic acid is CnH2n+1COOH. Among the given options, C2H5COOH (propanoic acid) is the only formula that contains the -COOH group, identifying it as a carboxylic acid [1]. Other options represent different functional groups: C3H7OH is an alcohol (propanol) [1], C3H8 is an alkane (propane) [2], and CH3COCH3 is a ketone (acetone or propanone) [2]. Carboxylic acids are named with the suffix '-oic acid' [1]. For example, when n=3 in the general formula, the compound is propanoic acid (C2H5COOH), which is soluble in water and exhibits hydrogen bonding.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Table 4.4 Nomenclature of organic compounds > p. 68
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.2.2 Chains, Branches and Rings > p. 64