Verified answer

Use PV = nRT to calculalte the volume occupied by 1.00 mol of oxygen gas:

(0.98 bar) (x) = (1.00 mol) (0.0831447 L bar per mol K) (298 K)

Once you have the volume (note that it is in liters), do this:

32.0 g divided by the volume.

This gives you the density in g/L, the usual unit for gas density.

I got the value for R here:

http://www.katmarsoftware.com/gconvals.htm