What is the molecular mass of a gas that diffuses through a porous membrane 1.86 times faster than Xe?

Answer 1

I would assume a convenient number for the rate of Xe, say something like 5 L/min. Then rate unknown gas, x, is 1.86*5.
(rate x/rate Xe) = (MM Xe/MM X)
Solve for MM = molar mass X.