Carboxylic Acids Molecules

The web album shows different carboxylic acid molecules. Please study the molecular structure carefully and answer the following questions.

1. Identify the functional group of carboxylic acid molecules.
2. Draw the structural formulae of different members of carboxylic acids.
3. Write the molecular formula of carboxylic acids
4. Naming  of carboxylic acid molecules using IUPAC nomentracture. The first member of carboxylic members with only one carbon atom. Its name is methanoic acid.  Please try to name other carboxylic acid molecules.