[alancalverd]

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/atmospheric-stratification  if anyone really cares that much

[Petrochemicals]

Oxygen and hydrogen are reasonably close in density,

Which is why hydrogen balloons don't fly.

Sorry, nitrogen.

[Bored chemist]

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/atmospheric-stratification  if anyone really cares that much

Obviously, I have done the calculation- I wouldn't be so sure of myself if I hadn't.

But what I'm trying to do is get you to do it so you realise how small the effect is.
Can you?

[alancalverd]

Very small, like I said. But > 0 is not = 0, which is why balloons fly and centrifuges are strategic targets.

[Bored chemist]

Very small, like I said. But > 0 is not = 0, which is why balloons fly and centrifuges are strategic targets.

So, have you got to grips with the fact that this

Methane is actually lighter than air but mains gas contains butane and ethane which will pool at the bottom

is nonsense?