Which aqueous solution has the lowest freezing point?

Calculate the molar mass of the solute when $1.5 \ g$ of a non-volatile solute is dissolved in $100 \ mL$ of a solvent having a density of $0.8 \ g \ mL^{-1}$,which lowers its freezing point by $0.75 \ K$. (Freezing point depression constant for the solvent is $5 \ K \ kg \ mol^{-1}$).

When $1.25 \ g$ of a non-volatile solute is dissolved in $20 \ g$ of water,the freezing point of the solution is found to be $271.9 \ K$. If the molal depression constant $(K_f)$ is $1.86 \ K \ kg \ mol^{-1}$,what is the molar mass of the solute?

$1\%$ solution of $Ca(NO_3)_2$ has a freezing point:

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 $= 1.86 \ K \ kg \ mol^{-1}$)

In cold countries,ethylene glycol is added to water in the radiators to: