In the Deacon process for the manufacture of chlorine, HC1 and O2 react to form Cl2 and H20

In the Deacon process for the manufacture of chlorine, HC1 and O2 react to form Cl2 and H20. Sufficient air (21 mole% 02, 79% N2) is fed to provide 35% excess oxygen and the fractional conversion of HCI is 85%.
(a) Calculate the mole fractions of the product stream components using atomic species balances in your calculation.
(b) Again calculate the mole fractions of the product stream components, only this time use the extent of reaction in the calculation.
(c) An alternative to using air as the oxygen source would be to feed pure oxygen to the reactor. Running with oxygen imposes a significant extra process cost relative to running with air, but also offers the potential for considerable savings. Speculate on what the cost and savings might be. What would determine which way the process should be run?