A wetted wall tower is used to “aerate” water using air at 2.0 atm total system pressure and 20°C. The molar composition of air is 21% O₂, 78% N₂, and 1% other gases. Let solute A = O₂. At 20°C, the Henry’s law constant for dissolution of O₂ gas in water is H = 40,100 atm based on the definition p_A,i = H _xA,i, and the mass density of liquid water is 1000 kg/m³. 

a. What is the maximum possible composition (as mole fraction) of oxygen (O₂) dissolved that could be dissolved in the water, x^*_A? 

b. What is the maximum possible molar concentration of oxygen (O₂) that could be dissolved in water, c^*_AL?

c. If the total system pressure is increase to 4.0 atm, what is the new the dissolved oxygen concentration?