Suppose that 200. J of energy is taken as heat from a hot source at 400.°C, passes through a turbine that converts some of the energy into work, and then releases the rest of the energy as heat into a cold sink at 20. °C. What is the maximum amount of work that can be produced by this engine if overall it is to operate spontaneously? What is the efficiency of the engine, with work done divided by heat supplied expressed as a percentage? How could the efficiency be increased?