Question

What are the main two allotropes of carbon? Distinguish these two allotropes on the basis of hardness and electrical conduction.

Answer 1

Allotropy, also known as allotropism. Some chemical elements exists in two or more distinct forms in the same physical state, known as allotropes.

The two main allotropes of Carbon ($\mathrm{C}$) are Diamond and Graphite.

We can distinguish the allotropes of the Carbon ($\mathrm{C}$) on the basis of hardness and electrical conduction and in detail they are as follows:

Property	Diamond	Graphite
Hardness	It is extremely hard because of the rigid, tetrahedral arrangement of carbon atoms.	Graphite is soft because the hexagonal layers of the carbon atoms can slide over each other.
Electrical Conduction	Diamond is an insulator because all the four electrons on each carbon atom are in covalent bonding, therefore no valence electron left in the diamond.	Graphite is a conductor because out of four valence electrons, three are going to be involved in covalent bonding while the last one which is free can conduct the electricity.