The stream from a gas well is a mixture containing 50 mol % methane, 10 mol % ethane, 20 mol % propane, and 20 mol % n-butane. This stream is fed into a partial conderser maintained at a pressure of 250 psia, where its temperature is brought to 80 degrees F. Determine the molar fraction of the gas that condenses and the compositions of the liquid and vapor phases leaving the condenser.