A mixture of non-volatile oil (MW=290) and butane is fed to a packed tower. It contains 4 moles % butane. Superheated steam at 140C is fed at the rate of 1 kmol/30 kmols of butane-free oil used. The outgoing liquid stream contains 0.04 % butane. Calculate the following: (a) composition of the exit gas stream and (b) the mass flow rate of the exit liquid stream