1) We apply the ideal gas equation: PV = nRT n = (21300 x 3/1000) / (8.314 x 323) n = 0.024 Your answer is correct.
2) Total pressure = Partial pressure of Hydrogen + Partial pressure of water 134.7 = 122.4 + Pw Pw = 12.3 kPa Your answer is correct
3) The molar fraction, volume fraction and pressure fraction of gasses are the same thing. Thus, percentage pressure of Oxygen = 10% Pressure of Oxygen = 2.04 x 10⁴ x 0.1 = 2.04 x 10³ kPa Your answer is correct
