A gas mixture with a total pressure of 750 mmHg contains each of the following gases at the indicated partial pressures: CO2 , 124 mmHg ; Ar , 218 mmHg ; and O2, 197 mmHg . The mixture also contains helium gas. What is the partial pressure of the helium gas?
What mass of helium gas is present in a 13.0-L sample of this mixture at 282 K?