Can the following problems be solved uniquely?

(a) The feed streams to an adiabatic equilibrium stage consist of liquid and vapor streams of known composition, flow rate, temperature, and pressure. Given the stage (outlet) temperature and pressure, calculate the composition and amounts of equilibrium vapor and liquid leaving the stage.

(b) The same as part (a), except that the stage is not adiabatic.

(c) A multicomponent vapor of known temperature, pressure, and composition is to be partially condensed in a condenser. The outlet pressure of the condenser and the inlet cooling water temperature are fixed. Calculate the cooling water required.