Can an element be broken down into simpler substances

State one important difference between a physical change and a chemical change?

In the experiment you asked to react hydrochloric acid and with sodium hydroxide. when measuring the volume of the reactants, which instrument would give the greatest precision.

#7 how does the structure of amino acids allow them to form a polypeptide? each amino acid has an amino group and a carboxyl group. each amino acid has a hydrogen atom and a carboxyl group. each amino acid has a carboxyl group and an r group. each amino acid has an r group and a hydrogen atom.