Question

Polymers are formed by joining several units called monomers.what does the term monomer refer to?
the answers are
a unit made up of several compounds
a unit made of several atoms
a unit made of several molecules

Answer 1

A monomer is a molecule, which means that it is a group of two or more atoms, which are bound in a chemical bounds. So the correct answer is a unit made of several atoms. 

Answer 2

The term monomer refers to :

a unit made up of several atoms

Explanation:

A monomer is a molecule that "can support polymerization whereby providing constitutional units to the fundamental structure of a macromolecule". Large quantities of monomers combine to form polymers in a method called polymerization.