The mole fraction of a solute in a solution is 0.1 . At 298 K , molarity of this solution is the same as its molality. Density of this solution at 298 K is $2.0 \mathrm{~g} \mathrm{~cm}^{-3}$. The ratio of the molecular weights of the solute and solvent, $\left(\frac{\mathrm{MW}_{\text {solute }}}{\mathrm{MW}_{\text {solvent }}}\right)$, is.