A piston$-$cylinder device contains steam initially at $1$MPa,$450C,$ and $2\mathrm{.}5m^3.$ Steam is allowed to cool at constant pressure until it first starts condensing. Show the process on a T$-$v diagram with respect to saturation lines and determine $($a$)$ the mass of the steam, $($b$)$ the final temperature, and $($c$)$ the amount of heat transfer. $(20$ points$)$