Please answer the questions

Arock can be broken down into different kinds of substances by physical processes. no chemical reactions are needed to separate different parts of a rock into pure substances. this is because a rock is a(n)

An atom with 7 protons, 6 neutrons, and 7 electrons has an atomic mass of amu. (enter a whole number.) numerical answers expected! answer for blank 1:

#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.