General Knowledge - General Science - Discussion

I think the correct answer is option A Graphite.

As graphite is an allotrope of Carbon, it shows a layering structure. Pencil cast an impression on paper because graphite is made up of carbon atoms and paper is made up of cellulose. Cellulose is an organic polysaccharide compound as we know all organic compounds are made up of carbon atoms. So both paper and graphite have carbon atoms in common so the carbon atom of graphite makes a covalent bond with the carbon atom of paper so the mark is cast. As graphite is mettloid its conductivity decreases with increase in temperature. It's color is black because when carbon black is heated to very high temperature for a long time then graphite is made. So, graphite is made from carbon black so the color of graphite is also black.

Nice explanation. Thanks all.

Graphite has layered structures of layers which are linked by van der Waal forces. Graphite cleans easily between the layers and therefore, it is very soft and slippery. For this reason, it is used in pencil and as lubricants in machines running at high temperature.

Yes, Graphite is used in pencils to write.

Yeah, graphite used in pencil.

In pencils the graphite is mixed with clay to change the hardness of the Lead. This accounts for its low hardness. This is because the layers can slide over each other easily. In fact the lead in pencil is not pure.

Then, what about charcoal pencils?

Graphite is an allotrope of carbon and hence a non-metal. But still, it conducts heat & electricity due to its structure.

It is used as lubricants (substances reducing friction) and made it easy to write.
This is why it is used for pencils.

Charcoal pencil are also used in drawing purpose.