At a certain temperature and pressure, 0.20 mol of carbon dioxide has a volume of 3.1 L. A 3.1-L sample of hydrogen at the same temperature and pressure ____.

Question

I think it's supposed to be "contains the same number of molecules" but I'm not sure.

And there's also this one. I think it's 1/3 also, but I'm not sure.

If the atmospheric pressure on Mt. Everest is one-third the atmospheric pressure at sea level, the partial pressure of oxygen on Everest is ___.

Answer 1

You are right on the first one.
On the second, it is 1/3 (without nitpicking about the composition of the atmosphere vs altitude).