Question

Graphite is a good conductor of electricity due to presence of
A. Lone pair of electrons
B. Free valence electrons
C. Cations
D. Anions

Answer 1

Hint: Graphite is generally found as a soft greyish black greasy substance. The term graphite is derived from the Greek word having the meaning write because when graphite is mixed with clay it forms lead which is used in pencils therefore graphite is also known by the name black lead.

Complete Solution :
Like diamond and fullerene, graphite also exists as an allotrope of carbon therefore graphite can also be known by the name crystallized carbon in which the carbon atoms of graphite form a crystal pattern which is different from the carbon atom present in diamond. In graphite the carbon atoms are arranged in flat planes of hexagonal rings which are attached on one another and each carbon atom is attached to three other carbon atoms in the same plane. Thus we can say only three out of four valence electrons are used in carbon-carbon bonding and the fourth valence electron remains loosely or we can say move freely between the planes. This free electron is responsible for the electrical conductivity of graphite.
So, the correct answer is “Option B”.

Note: The main properties of graphite are it has a metallic luster and it is opaque to light. Specific gravity shown by graphite is 2.3 which shows that it is a good conductor of heat and electricity and at a very high temperature it can be transformed into artificial diamond.