Air initially at 1 atm and 500°R with a mass of 2.5 lb is contained within a closed, rigid tank. The air is slowly warmed, receiving 100 Btu by heat transfer through a wall separating the gas from a thermal reservoir at 800°R. This is the only energy transfer. Assuming the air undergoes an internally reversible process and using the ideal gas model, (a) determine the change in exergy and the exergy transfer accompanying heat, each in Btu, for the air as the system. (b) determine the exergy transfer accompanying heat and the exergy destruction, each in Btu, for an enlarged system that includes the air and the wall, assuming that the state of the wall remains unchanged. Compare with part (a) and comment. Let T0 5 90°F, p0 5 1 atm.