Suppose 1.7 mol of a monatomic ideal gas initially at 7.8 L and 290 K is heated at constant volume to 550 K, allowed to expand isothermally to its initial pressure, and finally compressed at constant pressure to its original volume, pressure, and temperature. During the cycle, what are (a) the net energy entering the system (the gas) as heat and (b) the net work done by the gas? (c) What is the efficiency of the cycle?