what is the molar mass of a gaseous organic compound with a density of 3.38 g/L at 40oC and a pressure of 1.97 atm?

Answer 1

Didn't Dr Russ work a problem just like this for you earlier? or almost like it anyway.
I would do this.
PV = nRT
n = moles = g/M where M = molar mass
PVM = gRT, then we can rearrange to
PM=(g/v)RT and g/v is grams/volume or density.Solve for M.

Answer 2

Thank you sir