Which of the following mixtures shows positive deviation from ideal behavior?

Liquids $A$ and $B$ form an ideal solution in the entire composition range. At $350 \ K$,the vapour pressures of pure $A$ and pure $B$ are $7 \times 10^3 \ Pa$ and $12 \times 10^3 \ Pa$,respectively. The composition of the vapour in equilibrium with a solution containing $40 \ \text{mole percent}$ of $A$ at this temperature is

Liquids $A$ and $B$ form an ideal solution. The vapour pressure of pure $A$ and $B$ are $50 \ mm \ Hg$ and $32 \ mm \ Hg$ respectively at $300 \ K$. One mole of liquid $A$ is mixed with $1$ mole of liquid $B$. What is the approximate mole fraction of $A$ in the vapour phase?

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

At $88\,^oC$,the vapor pressure of benzene is $900 \, \text{torr}$ and that of toluene is $360 \, \text{torr}$. What is the mole fraction of benzene in the mixture with toluene that will boil at $88\,^oC$ and $1 \, \text{atm}$ pressure,assuming it forms an ideal solution?

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?