The correct answer for the question that is being presented above is this one: "0.3."
Here it is how to solve.
Molecular mass of Ar = 40
Molecular mass of Ne = 20
Number of moles of Ar = 9.59/40 = 0.239
Number of moles of Ne = 11.12/20= 0.556
Mole fraction of argon = 0.239/ ( 0.239 + 0.556) = 0.3
