Which of the following is true when components forming an ideal solution are mixed?

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

Which of the following statements is correct regarding a solution of two compounds $A$ and $B$ exhibiting positive deviation from ideal behaviour?

An example of a near-ideal solution is:

Formation of a solution from two components can be considered as
$(i)$ Pure solvent $\to$ separated solvent molecules $\Delta H_1$
$(ii)$ Pure solute $\to$ separated solute molecules $\Delta H_2$
$(iii)$ Separated solvent and solute molecules $\to$ solution $\Delta H_3$
Solution so formed will be ideal if

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?