When 9.45 g of ClCH_2 COOH is added to 500 mL of water, its freezing point drops by 0.5^° C. The dissociation constant of ClCH_2 COOH is x × 10^-3.…

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