Two moles of an ideal gas with C_V* = 3R are confined in a piston-cylinder arrangement. The piston is frictionless and the cylinder contains no mechanism for shaft work. Initially, the temperature is 300 K and the pressure is 1 bar. The external atmospheric pressure is also 1 bar. Find the heat, work and change in internal energy of the gas if:

A. It is heated to 500 K at constant volume.

B. It is heated at constant pressure to 500 K.

C. It is compressed isothermally to 5 bar.