When a $60 \mathrm{~W}$ electric heater is immersed in a gas for 100 s in a constant volume container with adiabatic walls, the temperature of the gas rises by $5^{\circ} \mathrm{C}$. The heat capacity of the given gas is ___________ $\mathrm{J} \mathrm{K}^{-1}$ (Nearest integer)