The solution from the following with the highest depression in freezing point (lowest freezing point) is:

$1.24 \ g$ of $AX_2$ (molar mass $124 \ g \ mol^{-1}$) is dissolved in $1 \ kg$ of water to form a solution with a boiling point of $100.0156^{\circ} C$,while $25.4 \ g$ of $AY_2$ (molar mass $250 \ g \ mol^{-1}$) in $2 \ kg$ of water constitutes a solution with a boiling point of $100.0260^{\circ} C$. $K_{b}(H_2O) = 0.52 \ K \ kg \ mol^{-1}$. Which of the following is correct?

The $pH$ of a $0.1 \, M$ monobasic acid is measured to be $2$. Its osmotic pressure at a given temperature $T \, K$ is (in $, RT$)

For a dilute solution containing $2.5 \ g$ of a non-volatile non-electrolyte solute in $100 \ g$ of water,the elevation in boiling point at $1 \ atm$ pressure is $2^{\circ} C$. Assuming the concentration of solute is much lower than the concentration of solvent,the vapour pressure ($mm$ of $Hg$) of the solution is (take $K_{b}=0.76 \ K \ kg \ mol^{-1}$)

The difference between the boiling point and freezing point of an aqueous solution of urea containing $10.0 \ kg$ of water is $100.2372 \ ^oC$. How many grams of urea are dissolved in the solution? (Given: $K_b = 0.513 \ K \ kg \ mol^{-1}$,$K_f = 1.86 \ K \ kg \ mol^{-1}$)

$A$ solution containing $1.8 \ g$ of a compound (empirical formula $CH_2O$) in $40 \ g$ of water is observed to freeze at $-0.465 \ ^oC$. The molecular formula of the compound is ($K_f$ of water $= 1.86 \ K \ kg \ mol^{-1}$)