2 mol of oxygen at 27 °C are mixed with an unknown number of moles of steam at the same temperature and pressure. The volume and total pressure of the gas at the end of the mixing are 2 m³ and 250 kPa. 

Compute: 

(a) the partial pressures of the two gases in the mixture; (b) the number of moles of steam in the mixture; and (c) the change in entropy associated with the mixing process. Consider oxygen to be an ideal, diatomic gas and steam to be an ideal, nonlinear tri-atomic gas.