The substance which conducts current in the solid-state is
(1) diamond
(2) graphite
(3) iodine
(4) sodium chloride
Answer: (2) The structure of graphite is unlike most other network substances. It is formed in ‘sheets’ of carbon atoms, each of which is bonded to only three others. The fourth valence electron of the carbon atom is delocalized and can move between the different layers, therefore carrying an electrical charge through the network of carbon atoms, a conductor is a material that contains movable electric charges. Unlike diamond (another carbon allotrope), graphite is an electrical conductor, a semimetal. It is, consequently, useful in such applications as arc lamp electrodes. Graphite is the most stable form of carbon under standard conditions. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds.
