Question

Why is diamond hardest substance on Earth?

• A. Due to extended ionic bond formation
• B. Due to extended covalent bond formation
• C. Due to $s{p}^2$ hybridised carbons
• D. Due to multiple $\pi$ bond formation.

Answer 1

The correct option is B Due to extended covalent bond formation

It has a crystalline lattice in which each carbon atom is $s{p}^3$ hybridized.
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.

THEORY
Diamond:

• It has a crystalline lattice in which each carbon atom is $s{p}^3$ hybridized.
• Each carbon atom is linked to four other carbon atoms and the C-C bond length is 154 pm.
• 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.
• 

Uses of Diamond :

1. Used as an abrasive for sharpening hard tools.
2. In making dyes.
3. In the manufacture of tungsten filaments for electric light bulbs.