Why is the formula for CO2 Carbon Dioxide
and not Monocarbon Dioxide? Explain.

If there is only one atom for the first element in the chemical formula, the prefix mono is typically omitted from the name. For example, CO is carbon monoxide, not mono carbon monoxide. ... Thus the chemical formula for carbon dioxide is CO2, not C1O2.

Explanation:

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.

it would be a gas formation