You have 2.657 x 10^2 mL of oxygen gas (O2) at 7.02 x 10^2 mm of Hg and 46 oC.
What is the mass of the sample in milligrams?
Use PV = nRT and solve for n = number of moles. Then n = grams/molar mass and solve for grams. Convert to mg.
Remember to convert V to liters, T to kelvin, and p to atmospheres.