A gas absorption column is to be designed to remove 90.0% of the ammonia from an air stream containing 2.0 mol% ammonia. The absorbent is pure water. The column is to be packed with 50 mm metal Pall rings and will be operated at 30°C and 1 atm with a design gas-mass velocity of 800 lb/(h ft²) and with L/G = 1.35. For these conditions, the equilibrium constant is K = 1.20. 

(a) Calculate the height of packing required.
(b) Determine the percentage of flooding for these conditions. 

(c) The column is built and works according to specifications. However, after a few months it is decided to retrofit the column with new packing in order to attain 95.0% removal of the ammonia using the same height of packing. All other conditions are to remain the same. Select a new packing type and size that will be suitable for this retrofit. Make sure that flooding will not occur in the retrofitted column.