Question

Equal masses of Ne and Ar are placed in a rigid, sealed container. If the total pressure in the container is 1.2 atm, what is the partial pressure of Ar?

Answer 1

I would assume a number (any number for the masses). Ten(10) looks like a convenient number to choose.
mols Ne = 10/atomic mass Ne = ?
mols Ar = 10/atomic number Ar = ?
total mols = mols Ne + mols Ar

XAr = nAr/total mols
XNa = nNe/atotal mols

pAr = XAr x Ptotal
pNe = XNe x Ptotal

Answer 2

its 6 btw :)