Q. Diamond is harder than graphite.

 1140  173 IIT JEEIIT JEE 1993The p-Block Elements Report Error

Solution:

Graphite has a layered structure of hexagonal carbon rings stacked one over other which makes it slippery.
On the other hand, in diamond, each carbon is tetrahedrally bond to other four carbons extended in three dimensional space, giving a giant, network structure. Due to this reason, diamond is harder than graphite.