2.00 mole of a monoatomic ideal gas at 265 K undergoes isothermal expansion from an initial pressure of 8.00 bar to 1.00 bar. Assuming ideal gas behavior, calculate the work (w) and heat (q) if the expansion is done: (a) against a constant external pressure (irreversible). (b) reversibly and isothermally. (c) Calculate the change in internal energy U. Assume ! = 3/2. Why is U the same if the expansion is done reversibly or irreversibly