Question

Carbon dioxide is generally heavier than oxygen and nitrogen. Why does it not form lower layer in the atmosphere?

Answer 1

True, because CO2 has capability to absorb IR radiations and are heated and thus gets lifted up. Vibrational energy of C=O bonds lies in IR while this doesn't happens in N2 and O2.

Answer 2

Though carbon dioxide is heavier than air, but it has a tendency to mix with other gases of air and since the rest gases are found at higher altitude so the carbon dioxide could not be able to be in the lower layer of atmospheric air. 

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