Which functional group is found in amino acids but not nucleotides? carboxyl hydroxyl phosphate amino?

The correct answer is carboxyl group.
The carboxyl group is an organic functional group consisting of a carbon atom double bonded to an oxygen atom and single bonded to a hydroxyl group (COOH). It is the main functional group of carboxylic acid.  Carboxylic acids are found in acetic acid and the amino acids that are used to build proteins.

The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.