The vapour pressure of a solution of methyl alcohol and ethyl alcohol is represented as $P = 115 X_A + 140$,where $X_A$ is the mole fraction of methyl alcohol. The value of $\lim_{X_A \to 0} \frac{P_B^o}{X_B}$ is

Which of the following substances,when dissolved in water,causes the maximum decrease in the vapor pressure of water?

At $30^\circ C$,liquid $A$ and $B$ form an ideal solution. The total vapor pressure of a solution containing $1 \ mol$ of $A$ and $2 \ mol$ of $B$ is $250 \ mm \ Hg$. The total vapor pressure becomes $300 \ mm \ Hg$ when $1 \ mol$ more of $A$ is added to the first solution. What are the vapor pressures of pure $A$ and $B$ at the same temperature?

Calculate the relative lowering of vapour pressure if the vapour pressure of the pure solvent and the vapour pressure of the solution at $25^{\circ} C$ are $32 \ mm \ Hg$ and $30 \ mm \ Hg$ respectively.

Which of the following can be measured by the Ostwald-Walker dynamic method?

Calculate the mass of a non-volatile solute (molar mass $40 \, g \, mol^{-1}$) which should be dissolved in $114 \, g$ octane to reduce its vapour pressure to $80 \%$.