What is the molal elevation constant of solvent ?

The elevation in boiling point is given by the relation:

$\Delta T_b = K_b \times m$

where $\Delta T_b$ is the elevation in boiling point, $K_b$ is the molal elevation constant, and $m$ is the molality of the solution.

Rearranging the formula, we get:

$K_b = \dfrac{\Delta T_b}{m}$

Thus, the molal elevation constant is the ratio of the boiling point elevation to the molality of the solution.

Answer: ratio of boiling point elevation to molality of solution.