Air in a piston$-$cylinder device is initially at $2000$ kPa and $623$ K $.$ The mass of air in the device is

$150$ g $.$ It undergoes isothermal expansion to $500$ kPa $.$ It is then polytropically compressed to $2$

MPa ; the polytropic coefficient is $1\mathrm{.}2.$ It is then returned to its initial state through a constant

pressure compression process.

a$.$ Calculate the boundary work involved in each of the three processes.

b$.$ Calculate the net boundary work, all in kJ$.$