Which of the following will produce the maximum depression in freezing point of its aqueous solution?

The molal depression constant for water is $1.86 \, ^\circ C \, kg \, mol^{-1}$. The freezing point of a $0.05 \, m$ solution of a non-electrolyte in water is:

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 $117 \ g \ mol^{-1}$)

Given below are two statements $:$
Statement $(I) : NaCl$ is added to the ice at $0^{\circ} C$,present in the ice cream box to lower the freezing point of the mixture,which helps in keeping the ice cream frozen.
Statement $(II) :$ On addition of $NaCl$ to ice at $0^{\circ} C$,there is a depression in freezing point.
In the light of the above statements,choose the correct answer from the options given below $:$

The solution containing $6 \ g$ urea (molar mass $60$) per $dm^3$ of water and another solution containing $9 \ g$ of solute $A$ per $dm^3$ water freeze at the same temperature. What is the molar mass of $A$?

Ethylene glycol is used as an antifreeze in cold climates. The mass of ethylene glycol $(C_2H_6O_2)$ that should be added to $4 \ kg$ of water to prevent it from freezing at $-6 \ ^oC$ is ......... $g$.
($K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$,and molar mass of ethylene glycol $= 62 \ g \ mol^{-1}$)