For which of the following mixtures is $\Delta_{mix} H > 0$?

At $27^{\circ} C$,two liquids $A$ and $B$ form an ideal solution with mole fractions $0.67$ and $0.33$ respectively. If the vapour pressure of pure $A$ and $B$ at $27^{\circ} C$ are $300 \ mm$ and $450 \ mm$ respectively,the total vapour pressure of the solution in $mm$ is:

Which property is not found in an ideal solution?

Which of the following liquid pairs shows a positive deviation from Raoult's law?

What is meant by positive and negative deviations from Raoult's law and how is the sign of $\Delta_{mix} H$ related to positive and negative deviations from Raoult's law?

$A$ mixture of toluene and benzene boils at $100^{\circ} C$. Assuming ideal behaviour,the mole fraction of toluene in the mixture is closest to (Vapour pressures of pure toluene and pure benzene at $100^{\circ} C$ are $0.742 \ bar$ and $1.800 \ bar$,respectively. $1 \ atm = 1.013 \ bar$)