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

Liquids $A$ and $B$ form an ideal solution for all compositions of $A$ and $B$ at $25^{\circ} C$. Two such solutions with $0.25$ and $0.50$ mole fractions of $A$ have total vapor pressures of $0.3 \ bar$ and $0.4 \ bar$,respectively. What is the vapor pressure of pure liquid $B$ in $bar$?

Liquids $A$ and $B$ form an ideal solution over the entire range of composition. At temperature $T$,an equimolar binary solution of liquids $A$ and $B$ has a vapour pressure of $45 \ Torr$. At the same temperature,a new solution of $A$ and $B$ having mole fractions $x_A$ and $x_B$,respectively,has a vapour pressure of $22.5 \ Torr$. The value of $x_A / x_B$ in the new solution is . . . . . (Given that the vapour pressure of pure liquid $A$ is $20 \ Torr$ at temperature $T$)

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

What are the values of $\Delta H_{mix}$ and $\Delta V_{mix}$ for an ideal solution?

Which of the following is true when components forming an ideal solution are mixed?