Molarity of a solution of density 1.2 g/ml is 1 M. Molality of the same solution under similar conditions will be (Molar mass of solute = 200 g)

Molarity of the solution = 1M

Number of moles of solute = 1

Volume of the solution = 1000 ml

Density of the solution = 1.2 g/ml

Weight of the solution = V x d = 1200 g

Weight of solute = ${\mathrm{W}}_{\mathrm{solution}}-{\mathrm{W}}_{\mathrm{solute}}$

                          = (1200 - 200) g

                         = 1000 g

 $$\begin{gathered} \mathrm{molality} \left(\mathrm{m}\right) = {\mathrm{n}}_{\mathrm{solute}}\times \frac{1000}{{\mathrm{W}}_{\mathrm{solvent}}}; \\ \mathrm{molality} \left(\mathrm{m}\right) = 1\times \frac{1000}{1000}; \\ \mathrm{molality} \left(\mathrm{m}\right) = 1\mathrm{m} ; \end{gathered}$$