Which of the following has the lowest freezing point?

Find the depression in freezing point of a solution when $3.2 \ g$ of a non-volatile solute with a molar mass of $128 \ g \ mol^{-1}$ is dissolved in $80 \ g$ of solvent,given that the cryoscopic constant of the solvent is $4.8 \ K \ kg \ mol^{-1}$. (in $K$)

Calculate the cryoscopic constant $(K_f)$ of a solvent when $2.5 \ g$ of a solute is dissolved in $35 \ g$ of the solvent,which lowers its freezing point by $3 \ K$. (Molar mass of the solute is $117 \ g \ mol^{-1}$)

What is the value of $K_{f}$ if $30 \ g$ urea (molar mass $60$) dissolved in $0.5 \ dm^{3}$ of water decreases the freezing point by $0.15^{\circ}C$?

The freezing point of a $4 \%$ by weight aqueous solution of $A$ is equal to the freezing point of a $10 \%$ by weight aqueous solution of $B$. If the molecular weight of $A$ is $60$,then the molecular weight of $B$ is:

What will be the freezing point of a $1\%$ aqueous solution of $Ca(NO_3)_2$?