Which statement is correct for solutions?

If $ΔH_{mix} > 0$ and $ΔV_{mix} > 0$, then solutions show positive deviations.

The correct answer is Option (4) → If $ΔH_{mix} > 0$ and $ΔV_{mix} > 0$, then solutions show positive deviations.

Ideal solutions do not obey Raoult's law. (Incorrect). An ideal solution is defined as one that obeys Raoult's Law over the entire range of concentration and temperature.

For an ideal solution, $ΔH_{mix}>0$ and $ΔV_{mix}>0$ (Incorrect). For an ideal solution, the enthalpy of mixing ($ΔH_{mix}$) and the volume of mixing ($ΔV_{mix}$) are exactly zero. This means no heat is absorbed or evolved, and the volume of the solution is the sum of the volumes of the components.

If $ΔH_{mix}>0$ and $ΔV_{mix}>0$, then solutions show negative deviations. (Incorrect). A solution that shows negative deviations from Raoult's law has attractive forces between A-B greater than those between A-A and B-B. This stronger attraction leads to: * $ΔH_{mix}<0$ (exothermic) * $ΔV_{mix}<0$ (volume decreases) * $P_{observed}<P_{Raoult}$.

If $ΔH_{mix}>0$ and $ΔV_{mix}>0$, then solutions show positive deviations. (Correct). A solution that shows positive deviations from Raoult's law has weaker attractive forces between A-B than those between A-A and B-B. This weaker attraction leads to: * $ΔH_{mix}>0$ (endothermic) * $ΔV_{mix}>0$ (volume increases) * $P_{observed}>P_{Raoult}$.