singular or plural

[Unregistered]

Dear Teacher,
"A family of" can be treated as singular or plural.
in the sentence "A family of polyurethanes was synthesized...".
Here it should be "was" or "were".

[Jair dos Santos Correa]

I think it should be "was" because of the subject "A" family of ...
Regards.

[Tdol]

In American English there is a tendency to use a singular verb with a collective noun, while British English frequently uses the plural, so either could be used depending on your taste.