Which property is not found in an ideal solution?

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 mixtures shows a positive deviation from Raoult's law?

The boiling point of an equimolar ideal solution of hexane $(C_6H_{14})$ and heptane $(C_7H_{16})$ is $80 \ ^oC$. What is the boiling point of a mixture of hexane and heptane containing equal mass of both? The boiling points of pure hexane and pure heptane are $69 \ ^oC$ and $98 \ ^oC$ respectively.

$A$ mixture of benzene and toluene forms

On mixing $10 \ mL$ of acetone with $40 \ mL$ of chloroform,the total volume of the solution is