GENERAL KNOWLEDGE

Detailed explanation-1: -The structure extends in space and produces a rigid 3-D network of carbon atoms with directional covalent bonds throughout the lattice. It is very difficult to break extended covalent bonding which makes diamond the hardest substance on the earth.

Detailed explanation-2: -Boron nitride c-BN is chemically and thermally stable, and is commonly used today as a superhard machine tool coating in the automotive and aerospace industries. But cubic boron nitride is still, at best, just the world’s second hardest material with a Vickers hardness of around 50 GPa.

Detailed explanation-3: -Each carbon atom in a diamond contains four electrons in its outer shell, which are shared by covalent connections with four other carbon atoms. This arrangement aids in the formation of a tetrahedral crystal that is rigid. Diamond is one of the hardest things on the planet because of its densely linked structure.