An ideal gas \( \vec{C}_V = \dfrac{5}{2} R \), is expanded adiabatically against a constant pressure of \( 1 \ \mathrm{atm} \) until it doubles in volume. If the initial temperature and pressure is \( 298 \ \mathrm{K} \) and \( 5 \ \mathrm{atm} \), respectively then the final temperature is ________ \( \mathrm{K} \) (nearest integer). [\( \vec{C}_V \) is the molar heat capacity at constant volume]