Question

Why are nonmetals poor conductors of electricity?
A. They have high melting point
B. They vibrate at high speed
C. They do not have free electrons
D. All of above

Answer 1

Hint: We know that conducting takes place due to the movement of the electrons. So, to answer this question we should be knowing the process of conduction of electricity. If we know that, we can classify the materials (metals and non-metals) as good or bad conductor electricity.

Step by step answer:
Most of the metals are considered as good conductors of electricity. This is because when metal atoms combine with each other, the outermost electrons lose contact with their parent atoms. The remaining positively charged atomic centres form an ordered structure while the outer electrons move freely around the whole sample.
On the other hand, in case of non-metals the conduction electrons are held tightly by the nucleus. So they cannot move easily. Hence, the non-metals are not good conductors of electricity.
However, non-metals can also become good conductors of electricity if external energy is applied to them, which makes the conduction electrons feasible.
Therefore, the non-metals are considered as poor conductors of electricity because they do not have free electrons. So, the correct answer is Option C.

Additional Information:
Graphite is a non-metal and it is the only non-metal that can conduct electricity.

Note: Non-metals are considered as insulators because they have extremely high resistance to the flow of charge through them. The atoms hold onto their electrons tightly and so they cannot conduct electricity.