The unit of Boiling point Elevation Constant ($K_b$) is

$K\, kg\, mol^{-1}$

The correct answer is Option (1) → $K\, kg\, mol^{-1}$

• Boiling point elevation is given by:

$\Delta T_b = K_b \cdot m$

where:

• $\Delta T_b$​ = elevation in boiling point (K)
• m = molality of solute (mol/kg)

Rearranging for Kb:

$K_b = \frac{\Delta T_b}{m} ⇒\text{units of } K_b = \frac{\text{K}}{\text{mol/kg}} = \text{K·kg·mol}^{-1}$

 Hence, the unit is K·kg·mol^-1.