Carboxylic acids are not hydrocarbons as they contain an two oxygen atoms. 
They have the functional group ‘-COOH‘ in their molecule. 

They are also unsaturated as they contain a ‘C = O’ bond in their molecule. 

They have the general formula: CnH₂n₊₁COOH
If (n = 3), the compound would be:
C₃H₂₍₃₎₊₁COOH = C₃H₇COOH

Every carboxylic acid’s name ends in ‘-oic acid’.

An acid’s prefix always changes according the number of carbon atoms present in the compound. 

Some common Carboxylic Acids:

Name of the AlcoholNo. of Carbon atomsFormula
Methanoic acid1HCOOH
Ethanoic acid2CH₃COOH
Propanoic acid3C₂H₅COOH
Butanoic acid4C₃H₇COOH
Pentanoic acid5C₄H₉COOH
Hexanoic acid6C₅H₁₁COOH
Heptanoic acid7C₆H₁₃COOH
Octanoic acid8C₇H₁₅COOH
Nonanoic acid9C₈H₁₇COOH
Decanoic acid10C₉H₁₉COOH