Solutions Questions

A $5.25\%$ solution of a substance is isotonic with a $1.5\%$ solution of urea (molar mass $=60{\text{g mol}}^{-1}$) in the same solvent. If the densities of both the solutions are assumed to be equal to $1.0{\text{g cm}}^{-3}$, molar mass of the substance will be:

A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of $290\text{mm}$ at $300\text{K}$. The vapour pressure of pure propyl alcohol is $200\text{mm}$. If the mole fraction of ethyl alcohol is $0.6$, its vapour pressure in pure state at the same temperature will be: