Answer:
Florine, Neon, Chlorine and Argon.
Explanation:
The density of a gas varies in direct proportion with its molecular mass. This means, higher molecular mass gases would have higher density and vice versa.
Increasing Density = Increasing Molecular mass
Arranging Argon, Florine, Neon and Chlorine in order of increasing molecular mass, we have;
Florine, Neon, Chlorine and Argon.
