State the reason why carbon can neither form `C^(4+)` cation nor `C^(4-)` anions, but forms covalent compounds. Also reasons to explain why covalent compounds:
(a) are bad conductors of electricity?
(b) have low meeting and boiling points?

Explanation

Carbon atoms have 4 electrons in their outermost shell. So needs to gain or lose electrons to attain noble has configuration.
- It could gain four electrons forming `C^(4-)` anion. But is would be difficult for the nucleus with six protons to hold on to ten electrons.
- It could loss four electrons forming `C^(4+)` cation. But it would require a large amount energy to remove four electons from its outermost shell.
Because of these reasons, carbon shares its valence electrons to complete its octet with other atom to form covalent bonds.
(a) Covalent compounds are bad conductors of electricity because they do not contain ions.
(b) Covalent compounds have usually low meeting and boiling point because they are made up of electronically neutral molecules. So the force of attraction between the molecules of a covalent compound is very weak. Only a small amount of heat energy is required to break these weak molecular forces, due to which covalent compounds have low melting and boiling points.