At a certain temperature the gasses sulfur dioxide and oxygen react to form the gas sulfur trioxide. Kp for this reaction is 2 x 10 5. If 1 atm of SO2 and 1 atm of O2 are injected into an evacuated rigid vessel, will the partial pressure of O2 at equilibrium be closest to 0 atm, 0.5 atm, 1 atm or 1.5 atm? Justify your answer.