An ideal gas, C̄_V =5/2 R, is expanded adiabatically against a constant pressure of 1 atm untill it doubles in volume. If the initial temperature and…

An ideal gas, $\displaystyle \overline{\mathrm{C}}_{\mathrm{V}}=\frac{5}{2} \mathrm{R}$, is expanded adiabatically against a constant pressure of $\displaystyle 1$ atm untill it doubles in volume. If the initial temperature and pressure is $\displaystyle 298$ K and $\displaystyle 5$ atm , respectively then the final temperature is $\displaystyle \_\_\_\_$ K (nearest integer). [ $\displaystyle \overline{\mathrm{C}}_{\mathrm{v}}$ is the molar heat capacity at constant volume]