Which one of the following solutions has the maximum vapour pressure at $27\,^{\circ}C$ temperature?

If two substances $A$ and $B$ have $P_A^0 : P_B^0 = 1 : 2$ and have mole fraction in solution $1 : 2$,then what is the mole fraction of $A$ in the vapour phase?

At $25\, ^oC$,benzene and toluene form an ideal solution. What will be the vapor pressure (in $mm \, of \, Hg$) of a solution containing benzene and toluene in a weight ratio of $1:2$? The vapor pressures of pure benzene and pure toluene are $75\, mm \, of \, Hg$ and $30\, mm \, of \, Hg$,respectively.

At the same temperature,which of the following will have the highest vapor pressure?

$1 \ mol$ of heptane $(V.P = 92 \ mm \ Hg)$ is mixed with $4 \ mol$ of octane $(V.P = 31 \ mm \ Hg)$. The vapor pressure of the resulting ideal solution is .......... $mm \ Hg$.

$3 \ g$ of urea is dissolved in $45 \ g$ of water. The relative lowering of vapour pressure is