Which of the following aqueous solutions will show maximum vapour pressure at $300 \text{ K}$?

Vapour pressure of a solution is

At $350 \ K$,the vapour pressure of pure liquids $A$ and $B$ are $450 \ mm \ Hg$ and $700 \ mm \ Hg$ respectively. If the total vapour pressure of the liquid mixture is $600 \ mm \ Hg$,the mole fractions of $A$ and $B$ in the vapour phase respectively are:

$9 \ g$ anhydrous oxalic acid (mol. $Wt. = 90$) was dissolved in $9.9 \ moles$ of water. If vapour pressure of pure water is $P_1^o$,the vapour pressure of solution is (in $P_1^o$)

At $300 \ K$, $0.06 \ kg$ of an organic solute is dissolved in $1 \ kg$ water. The vapour pressure of the solution at $300 \ K$ is $3.768 \ kPa$. If the vapour pressure of water at that temperature is $3.78 \ kPa$, what is the molar mass of the organic solute (in $g \ mol^{-1}$)? (Assume the solution is dilute)

If $x \ g$ of a non-volatile,non-electrolytic solute is dissolved in $114 \ g$ of octane to reduce its vapour pressure to $80 \%$ of that of pure octane,then $x$ is ........... $g$. (Molar mass of solute $= 40 \ g/mol$)