The normal freezing point of a certain liquid $x$ is $-9\mathrm{.}1C,$ but when $64\mathrm{.}9g$ of urea $((N{H}_2{)}_{2}CO)$ are dissolved in $850.g$ of $x,$ it is found that the solution freezes at $-12\mathrm{.}8C$ instead. Use this information to calculate the molal freezing point depression constant $K_f$ of $x_{.}$

Be sure your answer has the correct number of significant digits.

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