posted by samantha(very important) .
A gas mixture with a total pressure of 745mmHg contains each of the following gases at the indicated partial pressures: CO2, 257 mmHg; Ar, 123mmHg; and O2, 160 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 10.1L sample of this mixture at 263 K?