Why do the vinegar and oil in a salad dressing separate into layers if left standing for too long?

Which of the following units is not an official si unit

Condensation happens when water vapor cools. true or false? ?

#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.