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Question #44860
The Question
Consider the hexaaqua complexes of \ce{Cr^{3+}}, \ce{Cr^{2+}}, \ce{Mn^{3+}}, and \ce{Mn^{2+}} in an aqueous medium at . The standard reduction potentials are and .
Let = Magnitude of the Crystal Field Stabilization Energy (CFSE) in units of (ignoring pairing energy) for the hexaaqua complex that corresponds to the more negative value. Let = Total number of unpaired electrons in the ground state of the hexaaqua complex that corresponds to the highly positive value. Let = Number of complexes among the four mentioned above that experience strong Jahn-Teller distortion. Let = Number of -electrons in the metal ion of the complex that acts as the strongest reducing agent among the four. Let = Number of -electrons in the metal ion of the complex that acts as the strongest oxidizing agent among the four.
Calculate the value of the expression: .
Options
- A.
36
- B.
30
- C.
32
- D.
35
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Exception_Exposure
Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.
Concepts Behind This Question
E° (M³⁺/M²⁺) Redox Potential|Magnetic Moment Quenching|Color and d-d Transitions
Why This Question Is Tricky
Common Mistakes
The question tests the thermodynamic drivers behind the anomalous values for Cr and Mn.
Students often fall into the 'Magnetic Quenching Trap', assuming that the high reduction potential of \ce{Mn^{3+}} implies a low-spin state () to justify its instability.
In reality, \ce{[Mn(H2O)6]^{3+}} is high-spin () and its high is driven by the massive 3rd ionization energy required to break the exchange energy of \ce{Mn^{2+}}.
Furthermore, the question rigorously tests the conditions for strong Jahn-Teller distortion (asymmetric filling) and the identification of redox agents based on -electron configurations.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | D and F Block Elements - Class 12 |
| Concept | E° (M³⁺/M²⁺) Redox Potential |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |