A vertical piston$-$cylinder assembly containing $0\mathrm{.}5$ kg of ammonia, initially a saturated vapor, is placed on a hot plate. Due to the weight of the piston and the surrounding atmospheric pressure, the pressure of the ammonia is $1\mathrm{.}4$ atm $.$ Heating occurs slowly, and the ammonia expands at constant pressure until the final temperature is $25C.$ Show the initial and final states on T$-$v and p $-$v diagrams, and determine $($a$)$ the volume occupied by the ammonia at each state, in $m^3.($b$)$ the work for the process, in kJ