A domestic refrigerator maintains the freezer compartment at 260K while the kitchen air is at 300K. Answer the following questions with suitable reasoning.
(a) State the Clausius statement of the Second Law of Thermodynamics.
(b) Using the statement, explain why the refrigerator must be supplied with electrical work in order to transfer heat from the freezer to the kitchen.
(c) If the refrigerator could operate reversibly between these two temperatures, would the total entropy change of the universe for one complete cycle be positive, negative, or zero? Give a brief justification using symbols rather than numerical calculation.