we take a sample of an ideal, monatomic gas initially at 2.00 atm and with a volume of 10.0 l. in step 1, we allow it to expand isothermally against an external pressure of 1.0 atm until the new volume is 20.0 l. in step 2, we then compress the gas isothermally by applying an external pressure of 2.00 atm until it returns to its original volume. (a) what is w of the system for the overall process (i.e., for both steps)? (b) what is the change in internal energy for the overall process? (c) why are these values not the same? what would have to change about the steps to make them equal?