When 9.45 g of $\mathrm{ClCH}_2 \mathrm{COOH}$ is added to 500 mL of water, its freezing point drops by $0.5^{\circ} \mathrm{C}$. The dissociation constant of $\mathrm{ClCH}_2 \mathrm{COOH}$ is $\mathrm{x} \times 10^{-3}$. The value of x is $\_\_\_\_$ . (Rounded off to the nearest integer) $ \left[\mathrm{K}_{\mathrm{f}\left(\mathrm{H}_2 \mathrm{O}\right)}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right] $