Statement I : Diamond is an insulator and graphite is a conductor.Statement II : Diamond is used as abrasive and graphite as lubricant.

→ Diamond is non conductor of electricity due to lack of unpaired electronsWhere as graphite is good conductor of electricity due to the presence of decocalise electron in graphite→ Diamond is extremely hard subtance hence it is used as abrasive→ Where as graphite has layer like structure the layer are held by weak vander waal's force of attraction hence one layer slips over the other layer. Due to its slippery nature it is using lubricant.