Class NEET 2026 ALL Q #1982
COMPETENCY BASED
APPLY
4 Marks 2026 NTA-RE-NEET-2026 MCQ SINGLE
Assertion A: For an ideal solution formed by mixing liquids P and Q, $\Delta_{mix}H=0$ and $\Delta_{mix}V=0$. Reason R: No interactions occur between P and Q. In the light of the above statements, choose the most appropriate answer from the options given below.
(A) A is not correct but R is correct
(B) Both A and R are correct and R is the correct explanation of A
(C) Both A and R are correct but R is NOT the correct explanation of A
(D) A is correct but R is not correct
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Correct Answer: D

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Detailed Solution

Step 1: Analyze Assertion A

An ideal solution is defined as a solution that obeys Raoult's Law over the entire range of concentration. For such solutions, the enthalpy of mixing ($$\Delta_{mix}H$$) is zero, and the volume of mixing ($$\Delta_{mix}V$$) is zero. Thus, Assertion A is correct.

Step 2: Analyze Reason R

The reason states that no interactions occur between P and Q. This is scientifically inaccurate. In an ideal solution, the intermolecular forces of attraction between solute-solute (P-P) and solvent-solvent (Q-Q) are nearly equal to the solute-solvent (P-Q) interactions. It is not that "no interactions" occur; rather, the nature of the interactions remains unchanged upon mixing. Therefore, Reason R is incorrect.

Step 3: Conclusion

Since Assertion A is correct and Reason R is incorrect, the correct option is (D).

Final Answer: (D)

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student must apply the theoretical definition of ideal solutions to evaluate the validity of specific thermodynamic conditions and molecular interaction claims.
Knowledge Dimension: CONCEPTUAL
Justification: The question tests the understanding of the underlying principles of solution chemistry rather than rote memorization of facts.
Syllabus Audit: In the context of NEET, this is classified as COMPETENCY. It requires the student to distinguish between correct thermodynamic properties and the common misconception regarding molecular interactions in ideal solutions.

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