Question

Fill in the blank with either "insulators" or "conductors" to complete the sentence. the conductivity of a material is determined by the number of free electrons. have few or no free electrons.

Answer 1

The answer is insulators.

Insulators are the substances that have few or no free electrons.

Conductivity of a substance or material  is determined by the number of free electrons, Conductors are the substances that have large number of free electrons while insulators are the substances that have few or no free electrons.

So if a material has few or no free electrons than it must be characterized as insulator.

Answer 2

The Answer to the question is insulators.