a) What is gas absorption separation process [2 marks] b) Write down the physical significance of height of transfer units (HTU). [3 marks] c) A gas mixture containing 10 mol % SO2 and 90 mol % air at 1 atm total pressure and 30C is to be scrubbed with water to remove 97% of the SO2 in a tower packed with ceramic Rasching rings. The feed gas rate is 1500 kg/hr. If the equilibrium relation is given as shown in the equation below with the pinch point having the ordinate Y=0.0075 %3D 0.2X Y 1+ 0.8X %3D Where: Y and X are mole ratios of solute in gas and solvent streams respectively i) Determine the concentration of SO2 in the gas stream exiting the tower? [7 marks] ii) Calculate the minimum liquid flow rate using algebraic analysis method (not graphical method) [8 marks]