NEETChemistryCoordination Compounds
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In aqueous solution, Cr ²⁺ is strongly reducing while Mn ³⁺ is strongly oxidising, despite both having a d⁴ electronic configuration. Reason (R): The d³ configuration of Cr ³⁺ is highly stable due to a half-filled t_ 2g level, whereas the d⁵ configuration of Mn ²⁺ is highly stable due to an exactly
Options
- ABoth (A) and (R) are true but (R) is not the correct explanation of (A)
- BBoth (A) and (R) are true and (R) is the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
B. Both (A) and (R) are true and (R) is the correct explanation of (A)
Step-by-step solution
Assertion (A) is true. Both Cr ²⁺ and Mn ³⁺ have a d⁴ configuration. Cr ²⁺ acts as a reducing agent because it gets oxidised to Cr ³⁺ . Mn ³⁺ acts as an oxidising agent because it gets reduced to Mn ²⁺ . Reason (R) is true and correctly explains the Assertion. In an aqueous medium, the d³ configuration of Cr ³⁺ is exceptionally stable due to a half-filled t_ 2g set of orbitals in an octahedral crystal field. On the other hand, Mn ²⁺ has a d⁵ configuration, which is extra stable due to a symmetrical half-filled d -s