When a certain amount of a univalent salt AB (molar mass =54 ~g...

When a certain amount of a univalent salt AB (molar mass $=54 \mathrm{~g} \mathrm{~mol}^{-1}$ ) was dissolved in $0.1 \mathrm{dm}^3$ of water, the relative lowering of the vapour pressure was found to be $3.55 \%$. The molality of the resulting solution is: (Assume complete dissociation of the salt under given condition. Density of water $=1 \mathrm{~g} \mathrm{~cm}^{-3}$ )