Which of the following has the lowest freezing point?

The solution of sugar in water contains

An aqueous solution contains $6\%$ and $4\%$ by weight of a weak acid $(HA)$ and urea respectively. If the depression in freezing point is $\frac{13.6}{3} \, ^{\circ}C$,calculate the $K_a$ of $HA$. [Given: $K_f = 1.8 \, K \, kg/mol$,Molecular weight of $HA = 60$,$d_{solution} = 1 \, g/mL$]

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: $K_b = 0.513 \ K \ kg \ mol^{-1}$,$K_f = 1.86 \ K \ kg \ mol^{-1}$)

$1 \ g$ of silver gets distributed between $10 \ cm^3$ of molten zinc and $100 \ cm^3$ of molten lead at $800^{\circ} C$. The percentage of silver in the zinc layer is approximately

Two elements $A$ and $B$ form compounds having formula $AB_{2}$ and $AB_{4}$. When dissolved in $20 \ g$ of benzene $(C_{6}H_{6})$,$1 \ g$ of $AB_{2}$ lowers the freezing point by $2.3 \ K$ whereas $1.0 \ g$ of $AB_{4}$ lowers it by $1.3 \ K$. The molar depression constant for benzene is $5.1 \ K \ kg \ mol^{-1}$. Calculate atomic masses of $A$ and $B$.