Question

Assertion (A): Graphite is an allotrope of carbon (which is a non-metal). Though most non-metals are non-conductors of electricity, but graphite is a good conductor of electricity.

Reason (R): A carbon atom has 4 valence electrons in it. In a graphite crystal, each carbon atom is joined to only 3 other carbon atoms by covalent bonds. So, only the 3 valence electrons of each carbon atoms in graphite are used in bond formations. The 4^th valence electron of each carbon atom in graphite is free to move. Due to the presence of “Free electrons” in graphite, it conducts electricity.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is correct explanation of the assertion.

Explanation:

The assertion is true because graphite is a rare non-metal allotrope that conducts electricity exceptionally well. The reason is also true and provides the perfect explanation: because each carbon atom bonds to only three neighbours, the fourth valence electron remains free and delocalized, allowing electrical current to flow easily through the crystal lattice.