Question

Graphite is a good conductor of heat and electricity because it contains:
(A) Layers of carbon atoms.
(B) Sheet like structure.
(C) Free electrons.
(D) $\text{p }\pi \text{ -p }\pi$ bonding

Answer 1

Hint: Graphite is the crystalline allotropes of carbon. Graphite has a layered structure. Layers of graphite are held by the weak van der wall’s force of attraction. Each layer is composed of planar hexagonal rings of carbon and each carbon atom makes three sigma bonds with three neighbouring carbon atoms. The Fourth electron forms a $\pi$ bond.

Complete answer:
Due to the presence of free electrons graphite shows thermal and electric conductivity.
Graphite has two dimensional structures. In graphite, only three of the four valence electrons of each carbon atom are involved in bonding. Thus, each carbon atom makes use of $\text{s}{\text{p}}^{\text{2}}$-hybrid orbitals. Hence the fourth valence electron of each carbon atom remains unpaired or free. This free electron can easily move from one carbon atom to another carbon atom under the influence of applied potential. So this free electron is responsible for the conduction of heat and electricity.
Being a good conductor of electricity graphite is used for electrodes in batteries and industrial electrolysis.

Note:
In Graphite, layers are held together by weak van der wall’s forces. Graphite cleaves easily between the layers and therefore, it is very soft and slippery. For this reason graphite is used as a dry lubricant in machines running at high temperature where oil cannot be used as a lubricant.