Among the following substances,the lowest vapour pressure is exerted by

If two substances $A$ and $B$ have $P_A^o : P_B^o = 2 : 1$ and have mole fraction in solution $1 : 3$,then the mole fraction of $A$ in the vapour phase is:

The vapour pressure of pure $CCl_4$ (molar mass $= 154 \ g \ mol^{-1}$) and $SnCl_4$ (molar mass $= 170 \ g \ mol^{-1}$) at $25^{\circ} C$ are $115.0 \ torr$ and $238.0 \ torr$ respectively. Assuming ideal behaviour, calculate the total approximate vapour pressure in $torr$ of a solution containing $10 \ g$ of $CCl_4$ and $15 \ g$ of $SnCl_4$.

When a certain amount of solid $A$ is dissolved in $100 \ g$ of water at $25^{\circ} \ C$ to make a dilute solution,the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is $23.76 \ mm \ Hg$. The number of moles of solute $A$ added is $...........$ (Nearest Integer).

In a solution,the mole fraction of solute is $0.2$ when the lowering in vapour pressure is $10 \text{ mm Hg}$. To achieve a lowering of vapour pressure of $20 \text{ mm Hg}$,the mole fraction of the solute in the solution should be:

Calculate the weight of non-volatile solute having molecular weight $40$,which is dissolved in $57 \ g$ octane to reduce its vapour pressure by $20\%$.