For a gas sample whose total pressure is 740 torr, what are the partial pressures if the moles of gas present are 1.3 mol N2, 0.33 mol O2, and 0.061 mol Ar?

Answer 1

Calculate mols fraction each gas.
For example, XN2 = (mols N2/total mols)
Do the same for XO2 and XAr
Then peach = Xeach*Ptotal