Your company, for a carbon-credit exchange program, is considering a packed column to absorb CO₂ from air into a dilute-caustic solution. The air contains 3 mol% CO₂, and a 97% recovery of CO₂ is mandated. The air flow rate is 5,000 ft3/minute at 60^οF, 1 atm. It may be assumed that the equilibrium curve is Y = 1:75X, where Y and X are mole ratios of CO₂ to CO₂-free carrier gas and liquid, respectively. A column diameter of 2.5 ft with 2-inch Intalox saddle packing is assumed for the initial design estimates. Assume caustic solution has the properties of water. Calculate the: 

(a) Minimum caustic solution-to-air molar flow rate ratio, 

(b) Maximum possible concentration of CO₂ in the caustic solution, 

(c) Number of theoretical stages at L / V = 1:4 times the minimum, 

(d) Caustic solution rate, 

(e) Pressure drop per foot of column height (what does this result suggest?), 

(f) Overall number of gas transfer units, NOG, and 

(g) Height of packing, using a K_Ga of 2.5 lbmol/h-ft³-atm. Is this a reasonable way to get carbon credits?