$A$ mixture of benzene and toluene forms

Two liquids $X$ and $Y$ form an ideal solution. At $300 \ K,$ vapour pressure of the solution containing $1 \ mol$ of $X$ and $3 \ mol$ of $Y$ is $550 \ mm \ Hg.$ At the same temperature,if $1 \ mol$ of $Y$ is further added to this solution,vapour pressure of the solution increases by $10 \ mm \ Hg.$ Vapour pressure (in $mm \ Hg$) of $X$ and $Y$ in their pure states will be,respectively:

Which of the following liquid pairs does not show contraction in volume on mixing?

Which pair of liquids shows positive deviation from Raoult's law?

In a mixture of components $A$ and $B$,the components show negative deviation when:

At $373 \ K$,heptane and octane form an ideal solution. The vapor pressures of the two pure liquid components (heptane and octane) are $105 \ kPa$ and $45 \ kPa$,respectively. The vapor pressure of the solution formed by mixing $25 \ g$ of heptane and $35 \ g$ of octane is ........ $kPa$. (Molar masses of heptane and octane are $100 \ g \ mol^{-1}$ and $114 \ g \ mol^{-1}$,respectively.)