Which of the following solutions will exhibit the highest boiling point?

An aqueous dilute solution containing non-volatile solute boils at $100.52^{\circ} C$. What is the molality of the solution (in $m$)? ($K_b = 0.52 \ K \ kg \ mol^{-1}$, boiling temperature of water $= 100^{\circ} C$)

$2 \, g$ of a non-volatile non-electrolyte solute is dissolved in $200 \, g$ of two different solvents $A$ and $B$ whose ebullioscopic constants are in the ratio of $1: 8$. The elevation in boiling points of $A$ and $B$ are in the ratio $\frac{x}{y} (x: y)$. The value of $y$ is .... (Nearest integer)

$A$ solution is prepared by dissolving a $2.5 \ g$ sample of an unknown compound in $34 \ g$ of benzene,$C_6H_6$. The solution boils at $1.38 \ ^\circ C$ higher than pure benzene. Which expression gives the molar mass of the unknown compound? $K_b$ of $C_6H_6$ is $2.53 \ ^\circ C \ m^{-1}$.

The correct relation between the elevation in boiling point and the molar mass of a solute is: ($W_1$ and $W_2$ are respectively weight of solvent $\&$ solute)

$A$ solution containing $0.1050 \ g$ of a substance in $15.84 \ g$ of ether has a boiling point $1 \ ^\circ C$ higher than that of pure ether. What is the molar mass of the substance? [Given: Molar elevation constant for ether per $100 \ g = 21.6$]