$1-1)$ Please explain the reason why we need to use both phases $-$ liquid and vapor in a single Rankine cycle. Please, for example, use these keywords; pump work, specific volume, turbine work, back work ratio.

$1-2)$ Assume that $150C,30kW$ of process heat is required. If it can be given by using turbine exit gas at which temperature is $250C$ from Rankine cycle operation, can this cycle have $100\%$ of cogeneration utilization factor? If not, please explain the reason.

$1-3)$ Is it possible to maintain a pressure of $10$ kPa in a condenser that is being cooled by river water at $20C?$

$1-4)$ What is the difference between 'cogeneration' and 'regeneration' in Rankine Cycle?