A vertical piston-cylinder assembly contains argon. The piston has a mass of mass 25 kg and a face area of 0.005 m2. The mass of argon is 2.5 g, and initially the argon occupies a volume of 2.5 liters. The atmosphere exerts a pressure of 100 kPa on the top of the piston. During a process, the volume of the argon slowly decreases to 0.001 m3 as energy with a magnitude of 1 kJ is slowly removed by heat transfer. Determine the change in the specific internal energy of the argon, in kJ/kg, for this process. Assume the following:

a. g = 9.81 m/s^2
b. friction between the piston and the cylinder wall is negligible.
c. the change in the potential energy of the argon is negligible.
d. the change in the kinetic energy of the argon is negligible.