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

$A$ solution containing $7.5 \ g$ of urea (molar mass $= 60 \ g \ mol^{-1}$) in $1 \ kg$ of water freezes at the same temperature as another solution containing $15 \ g$ of solute $X$,in the same amount of water. The molar mass of $X \ (g \ mol^{-1})$ is

The freezing point of an aqueous solution containing $17 \ g$ of $C_2H_5OH$ in $1000 \ g$ of water is ......... $^oC$. (Given $K_f$ of water $= 1.86 \ K \ kg \ mol^{-1}$)

If the freezing point of a $5\% \ w/w$ aqueous solution of sucrose is $271 \ K$ and pure water has a freezing point of $273.15 \ K$,then calculate the freezing point of a $5\% \ w/w$ aqueous solution of glucose. (in $K$)

The freezing point of a $1\%$ aqueous solution of calcium nitrate will be:

If $0.072 \ g-atom$ of sulfur is dissolved in $100 \ g$ of solvent $(K_f = 7.00)$,the depression in freezing point is $0.84 \ ^\circ C$. The molecular formula of sulfur in the solution is .............