Question $1(45$ points$)$: This question has THREE parts.

A piston$-$cylinder assembly contains $0\mathrm{.}85$ kg of refrigerant $R-134a$ at $-20C.$ The

piston is free$-$floating with a diameter of $25$ cm and a mass of $5$ kg $.$ The local

atmospheric pressure is $59$ kPa $.$ Heat is added to R $-134$a until temperature

reaches $+20C.$ Find:

a$)$ The final pressure of the refrigerant $(15$ points$).$

b$)$ Change in the volume of the refrigerant $(15$ points$).$

c$)$ Change in the internal energy of the refrigerant $(15$ points$).$