two moles of an ideal monatomic gas initially at 300K and a pressure of 2 atm is compressed adiabatically using a constant external pressure Pext until equilibrium is reached. The temperature of the gas is then 400K

a) calculate w, q, delta U, and delta H for this process

b) calculate the final equilibrium pressure Pf of the gas (note Pf = Pext)

c) calculate delta S for this process.