An investigator is told that a closed vessel holds a pure rare gas. She measures the density of the gas in the vessel at 298K as well as 1atm pressure and finds it to be 0.8252g liter-1.
A) Explain what gas does the investigator think is in the vessel?
B) After turning in her report she is told that the vessel actually contains a mixture of He and Ar. Explain what percentage of the gas in the container is He?