Which of the following does not belong to an ideal solution?

All form ideal solutions except:

In a mixture of $A$ and $B$ components,the solution shows positive deviation from Raoult's law when:

Each pair forms an ideal solution except?

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