5.

What happens in a condensation reaction?

cross-linking of monomers

head-to-tail joining of monomers

side-by-side joining of monomers

substitution of a halogen on monomers

The answer is head-to-tail joining of monomers. Monomer used in condensation have two functional groups that combine to form amide and ester linkages. When this reaction occurs, water molecules is removed and that is why it is called a condensation reaction.