A piston-cylinder device initially contains 15 ft3 of helium gas at 25 psia and 70°F. Helium is now compressed in a polytropic process (PVconstant) to 70 psia and 300°F. Determine a. The entropy change of helinn (5%) b. The entropy change of the surroundings [5%] c. Whether this process is reversible, irreversible, or impossible. (3%) Assume the surroundings are at 70°F