# Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anomalous behaviour is that graphite Option 1) is a non-­crystalline substance Option 2) is an allotropic form of diamond Option 3) as molecules of variable molecular masses like polymers Option 4) has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.

As learnt in

Graphite -

C atom is sp2 hybridised and thermodynamically more stable than diamond at ordinary temperature

- wherein

High electrical conductivity is due to presence of delocalised $\pi -$ electron cloud.

and

Structure of Graphite -

Layered structure held by Van der Waals forces and each layer is formed by planar hexogonalrings of carbon which forms three sigma bonds with 3 neighbouring carbon atoms, fourth electron contributes in $\pi - bond$

-

Graphite has a layered structure held by Vander Waals forces and each layer is formed by planer hexagonal rings of carbon which form $3\sigma$ bonds with 3 neighbouring carbon atoms, fourth electron contributes in $\pi$ bond.

Carbon atoms in graphite draw Sp2 hybridization and form a two-dimensional sheet like structure. This structure is less compact than diamond and sheets of graphite slide over one another but like any crystalline structure, it has a higher melting point.

Option 1)

is a non-­crystalline substance

This option is incorrect.

Option 2)

is an allotropic form of diamond

This option is incorrect.

Option 3)

as molecules of variable molecular masses like polymers

This option is incorrect.

Option 4)

has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.

This option is correct.

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