A mixture of 75%mole propane and 25%mole hydrogen is burned with 25% excess air. Fractional conversions of 90% of the propane and 85% of the hydrogen are achieved; of the propane that reacts, 95% reacts to form CO2 and the balance to form CO. The hot combustion product gas passes through a boiler in which heat transferred from the gas converts boiler feedwater into steam. Calculate the concentration of CO (ppm) in the stack gas on a dry basis. Use extent of reaction species balance to solve.