A mixture of propane and butane is burned with pure oxygen. The combustion products contain 47.4 mole% H₂O. After all the water is removed from the products, the residual gas contains 69.4 mole % CO₂ and the balance O₂. 

(a) What is the mole percent of propane in the fuel? 

(b) It now turns out that the fuel mixture may contain not only propane and butane but also other hydrocarbons. All that is certain is that there is no oxygen in the fuel. Use atomic balances to calculate the elemental molar composition of the fuel from the given combustion product analysis (i.e., what mole percent is C and what percent is H). Prove that your solution is consistent with the result of Part (a).