AIIMS2018Chemistry-Coordination Compounds

AIIMS 2018 Chemistry Stability of Complexes Assertion Reason Question

Type: Assertion Reason-conceptual-Medium-Class 12

Assertion: [Co(NH₃)₆]³⁺ and [Co(en)₃]³⁺ are more stable complex. Reason: They are low spin complex.

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 B

Detailed Explanation

Option B is correct because both [Co(NH₃)₆]³⁺ and [Co(en)₃]³⁺ are indeed stable complexes due to their low spin configurations, which result from the pairing of electrons in the presence of strong field ligands like NH₃ and ethylenediamine (en). However, the assertion that they are more stable is not solely explained by being low spin; other factors such as steric effects and chelation in [Co(en)₃]³⁺ also contribute to their stability.

Option A is incorrect because, while both statements are true, the reason does not fully explain the assertion. Option C is wrong since the assertion is true, but the reason is also true. Option D is incorrect because both the assertion and reason are valid statements about the complexes.

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