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

At $300 \ K$,the vapour pressure of a pure liquid $A$ is $70 \ mm \ Hg$. It forms an ideal solution with another liquid $B$. The mole fraction of $B$ in the solution is $0.2$ and the total vapour pressure of the solution is $84 \ mm \ Hg$ at the same temperature. What is the vapour pressure (in $mm \ Hg$) of pure liquid $B$ at $300 \ K$?

Which of the following will form an ideal solution?

Which of the following pairs of liquids shows a negative deviation from Raoult's law?

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

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?