(a) A Carnot engine has an efficiency of 29%. Suppose we want to increase the Carnot efficiency to 35%, how much should the temperature of the hot reservoir increase? The temperature of the cold reservoir is fixed at 7 C. (6) (b) A heat engine takes in 850J of heat and does 250J of work in one cycle. (i) How much heat does it release in four cycles? (ii) What is the efficiency of the engine? (c) Explain whether an air conditioner is a heat engine or heat ump? (2) (2) (4)