A glass vessel fitted with an on/off value has a mass of 337.428g when evacuated. When filled with Ar, it has a mass of 339.712g. When evacuated and refilled with a mixture of Ne and Ar, under the same conditions of temperature and pressure, it weights 339.146g. What is the mole percentage of Ne in the gas mixture?
Atomic masses: Ne: 20.179 u ; Ar: 39.948 u