Which of the following does not show electrical conduction

Options

(a) Diamond
(b) Graphite
(c) Potassium
(d) Sodium

Correct Answer:

Diamond

Explanation:

Potassium and sodium are metals so have mobile electrons. In graphite, each of the C-atom is covalently bonded to three other C-atoms so one valence electron is available for electrical and thermal conduction there is no mobile electron present in diamond as each C-atom is bonded to four other C-atoms by covalent bond.