An amine

Select $2$ correct answer$($s$)$

may possess double bonds

is represented by the formula, $R-N{H}_2$

exists in each of the amino acids that are ligated via a peptide bond existing between the atoms of carbon of those amino acids

is represented by the formula, $R_2-NH$

exists in each amino acid as does $()-,$ which represents the ester of a carbonyl group

of one amino acid is connected to the acetyl group of an adjacent amino acid via a peptide bond