calculate the density of oxygen,O/2 under each of the followig conditions-stp,1.00 atm and 35.0 celsius?

Answer 1

You can modify the PV = nRT expression to become P*M = dRT where M is the molar mass and d is the density.
Substitute and solve for density for each of the conditions. The STP can be done more easily if you remember that any gas at STP occupies 22.4L.