Truly "inert" gases will never make a compound (molecule) with anything else, including themselves. Some of your "inert gases" though, like Xenon, CAN under special circumstances form compounds, like XeF6.
CO2 is ALREADY a compound, and can undergo other changes.
Nitrogen exists as a diatomic molecule, N2, meaning it has already reacted with itself. Plus, it is found in myriad other compounds, like ammonia.