Which of the following substances is a bad conductor of electricity?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Diamond
A substance conducts electricity when it has charges that are free to move. In diamond, each carbon atom is bonded to four others, so all four outer electrons are held in bonds and none is free to carry a current. Diamond is therefore a bad conductor (an insulator).
Why the other options are incorrect
Option (2) Gold — Incorrect. It is a metal, with free electrons that make it a very good conductor.
Option (3) Silver — Incorrect. It is a metal and the best conductor of electricity of all.
Option (4) Graphite — Incorrect. Like diamond it is pure carbon, but each atom bonds to only three others, leaving one free electron per atom, so it conducts.