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Q.
Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anomalous behaviour is that graphite
The Solid State
Solution:
Graphite has a two-dimensional sheet like structure and each carbon atom is $sp^2$ hybridised. The layer structure of graphite is much less compact than diamond. Since, the bonding between the layers involving only van der Waals’ forces is weak, these layers can slide over each other. This gives softness, greasiness and lubricating character to graphite.