The units of molality are

Molality of the solution can be expressed as number of gram moles of the solute present in 1kg of the solvent.

$\mathrm{m}=\frac{\mathrm{n}}{\mathrm{w}\left(\mathrm{kg}\right)}$

$\mathrm{Units}- \mathrm{mole}.{\mathrm{kg}}^{-1}$