Account for following

Account for the following.
(i) Graphite is used as lubricant.
(ii) Diamond is used as an-abrasive.

(i) Graphite has layered structure. Layers are held together by weak van der Waals forces and hence can be made to slip over one another. Therefore, graphite acts as a dry lubricant.
(ii) In diamond, each ${{sp}^{3}}$ hybridised carbon atom is linked to four other carbon atoms. It has three-dimensional network of carbon atoms. It is very difficult to break extended covalent bonding and therefore diamond is a hardest substance on the earth. That’s why it is used as an abrasive.