What is a non-ideal solution and what is meant by positive deviation from Raoult's law?

(N/A) non-ideal solution is a solution that does not obey Raoult's law over the entire range of concentration.
In a non-ideal solution,the solute-solute $(A-A)$ and solvent-solvent $(B-B)$ interactions are different from the solute-solvent $(A-B)$ interactions.
Positive deviation occurs when the vapor pressure of the solution is higher than that predicted by Raoult's law.
This happens when the solute-solvent $(A-B)$ interactions are weaker than the solute-solute $(A-A)$ and solvent-solvent $(B-B)$ interactions.
Consequently,the molecules escape more easily into the vapor phase,leading to an increase in total vapor pressure,$\Delta H_{mix} > 0$ (endothermic),and $\Delta V_{mix} > 0$ (expansion).