Ar $($a simple, ideal gas$)$ is fed to a vessel that has a movable piston, but that piston is initially held in place by a pin. The vessel is sealed with an initial pressure of $1$ bar and an initial temperature of $30$oC$.$ While the pin remains in place, the vessel is heated until the pressure reaches $4$ bar. Then, the pin is released and the system instantaneously expands $($too fast for heat transfer to occur$)$ until the final pressure is again $1$ bar. Find the expansion ratio for the process $($Vfinal$/$Vinitial$)$ and the final temperature $($in K$)$ of the Ar$.$