UPSC CDS Science Chemistry Questions Part 1

Graphite is used in making lead pencil. Graphite has a covalent structure made of carbon atoms. In graphite, each carbon atom is joined to three others, forming layers. The bonds between the layers are much weaker than the covalent bonds. This enables the layers to slide across each other, making graphite soft. As the pencil moves across the paper, layers of graphite rub off and leave marks on the paper.