AIIMS2018Chemistry-Coordination Compounds

AIIMS 2018 Chemistry Crystal Field Stabilization Energy MCQ Question

Type: MCQ-conceptual-Medium-Class 12

Assertion : [Cr(H2O)6]+2[Cr(H2O)6]+3[\text{Cr}(\text{H}_2\text{O})_6]^{+2} \rightarrow [\text{Cr}(\text{H}_2\text{O})_6]^{+3} while converting, colour continuously changes.

Reason : CFSE is increases during change.

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option A

Detailed Explanation

The CFSE (Crystal Field Stabilization Energy) value for [Cr(H₂O)₆]²⁺ is higher at –0.6Δ₀ compared to [Cr(H₂O)₆]³⁺, which has a CFSE of –1.2Δ₀. This indicates that [Cr(H₂O)₆]²⁺ experiences less stabilization due to its higher number of unpaired electrons in the 3d subshell, leading to a less negative CFSE value. Option B is incorrect because it suggests that [Cr(H₂O)₆]³⁺ has a higher CFSE, which contradicts the provided values. Options C and D are also incorrect, as the CFSE values can indeed be compared based on their numerical values.

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