Alanine, lysine and aspartic acid are amino acids - VCE - SSCE Chemistry - Question 6 - 2011 - Paper 1

In this question, the key point is to understand the behavior of amino acids in the presence of strong acids like hydrochloric acid (HCl). Amino acids contain both an amino group (-NH₂) and a carboxyl group (-COOH). When exposed to HCl, the amino group of an amino acid can accept a proton (H⁺), leading to the protonation of the amino group.

1. Lysine: This amino acid has a primary amino group that can easily react with HCl. Therefore, lysine will react with 1.0 M HCl.

2. Aspartic acid: This amino acid has both a carboxylic acid group and an amino group. The amino group will also accept protons in the presence of HCl, indicating that aspartic acid will react with HCl as well.

3. Alanine: Similar to the other two, alanine also features an amino and a carboxyl group, permitting it to react with HCl. Thus, alanine too will react with 1.0 M HCl.

Since all three amino acids (lysine, alanine, and aspartic acid) can react with HCl, the correct answer to the question is therefore option D.