During the depression of freezing point in a solution,which of the following are in equilibrium?

When $36 \ g$ of a non-volatile,non-electrolytic solute having the empirical formula $CH_2O$ is dissolved in $1.2 \ kg$ of water,the solution freezes at $-0.93 \ ^\circ C$. The molecular formula of the solute is ($K_f$ of water $= 1.86 \ K \ kg \ mol^{-1}$)

$A$ solution of $36 \ g$ of glucose $(C_6H_{12}O_6)$ in $1000 \ g$ of water is cooled to $-0.5 \ ^\circ C$. How many grams of ice would have separated from the solution? (Given: $K_f = 1.86 \ K \ kg \ mol^{-1}$)

$1.8 \ g$ of glucose (molar mass $180 \ g \ mol^{-1}$) is dissolved in $0.1 \ kg$ of water. The freezing point of the solution (in $^{\circ}C$) is ($K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$)

$A$ solution of a nonvolatile solute is obtained by dissolving $1 \ g$ in $100 \ g$ of solvent,which decreases its freezing point by $0.3 \ K$. Calculate the cryoscopic constant of the solvent if the molar mass of the solute is $60 \ g \ mol^{-1}$.

What is molal depression constant? Derive an equation.