$-$ A vertical piston$-$cylinder device initially contains $0\mathrm{.}25m3$ of air at $600$kPa and $300C.$ A

valve connected to the cylinder is now opened, and air is allowed to escape until three$-$

quarters of the mass leaves the cylinder at which point the volume is $0\mathrm{.}05m3.$ Determine $($a$)$

the final temperature in the cylinder, $($b$)$ the boundary work during this process, and $($c$)$ the

ratio between the system's specific energies before and after the process.