$A$ solvent freezes at $17^{\circ} C$ and it has a latent heat of fusion of $180 \ J \ g^{-1}$. The molal depression constant $(K_{f})$ of the solvent is (in $K \ kg \ mol^{-1}$):

At the freezing point of a solution containing a nonvolatile solute,which of the following are in equilibrium?

The depression in freezing point of a solution of molality $0.01 \ mol \ kg^{-1}$ is highest with respect to which of the following solvents? (The $K_f$ value is given in brackets)

Given below are two statements $:$
Statement $(I) :$ Molal depression constant $K_{f}$ is given by $\frac{M_1 R T_f^2}{1000 \Delta H_{\text {fus }}}$,where symbols have their usual meaning. (Note: The provided formula in the prompt was corrected to the standard thermodynamic expression $K_f = \frac{M_1 R T_f^2}{\Delta H_{\text {fus }}}$).
Statement $(II) :$ $K_{f}$ for benzene is less than the $K_{f}$ for water.
In the light of the above statements,choose the most appropriate answer from the options given below $:$

Which aqueous solution has the lowest freezing point?

The normal freezing point $(f.p.)$ of nitrobenzene is $278.82 \ K$. If a non-volatile solute is dissolved in it and a solution of $0.25 \ molality$ is prepared,the observed freezing point of the solution is $276.82 \ K$. Evaluate the cryoscopic constant $(K_f)$ of nitrobenzene in $K \ kg \ mol^{-1}$.