Calculate the work done in Joules when one mole of an ideal gas, initially at P = 9 atm, T = 298 K is expanded isothermally to P = 1 atm if (a) the expansion proceeds against a onstant external pressure Pext = 1 atm; (b) the external pressure is reduced in steps, from Pext = 9 atm to 7 atm, then from 7 atm to 5 atm, then from 5 atm to 3 atm, and finally from 3 atm to 1 atm; (c) the expansion is done reversibly. Which expansion extracts the maximum work from the gas?