RE-NEET 2026 Chemistry Ideal Solutions Assertion Reason Question

The principle here is that for an ideal solution, the enthalpy change of mixing ($\Delta_{mix} H$) and the volume change of mixing ($\Delta_{mix} V$) are both zero, indicating no heat is absorbed or released and no volume change occurs. This is true when the interactions between the components are similar to those in the pure substances.

In this case, while assertion A is correct, stating that $\Delta_{mix} H = 0$ and $\Delta_{mix} V = 0$, reason R is incorrect because it implies that no interactions occur, which is not true for ideal solutions; they still have interactions, just balanced. Thus, option B is correct as it acknowledges A's correctness while rejecting R's validity. Other options fail because they either incorrectly assert R's correctness or misinterpret the relationship between A and R.