NEETChemistryd and f Block Elements
Despite having the same d^4 electronic configuration, Cr ²⁺ acts as a strong reducing agent while Mn ³⁺ acts as a strong oxidising agent. What is the correct reason for this contrasting behaviour?
Options
- ACr ²⁺ is oxidised to Cr ³⁺ which has a stable d^5 configuration, while Mn ³⁺ is reduced to Mn ²⁺ which has a s
- BMn ³⁺ acts as an oxidising agent to achieve a stable d^0 configuration, while Cr ²⁺ acts as a reducing agent t
- CCr ²⁺ is reduced to Cr ⁺ which has a stable half-filled d -subshell, while Mn ³⁺ is oxidised to Mn ⁴⁺ which ha
- DCr ²⁺ is oxidised to Cr ³⁺ which has a stable half-filled t_ 2g level ( d^3 ), while Mn ³⁺ is reduced to Mn ²⁺
Correct answer
D. Cr ²⁺ is oxidised to Cr ³⁺ which has a stable half-filled t_ 2g level ( d^3 ), while Mn ³⁺ is reduced to Mn ²⁺
Step-by-step solution
A reducing agent gets oxidised, meaning it loses an electron. Cr ²⁺ ( d^4 ) loses one electron to form Cr ³⁺ ( d^3 ). In an aqueous medium, the d^3 configuration is exceptionally stable due to an exactly half-filled t_ 2g level. An oxidising agent gets reduced, meaning it gains an electron. Mn ³⁺ ( d^4 ) gains one electron to form Mn ²⁺ ( d^5 ). The d^5 configuration is highly stable due to an exactly half-filled d -subshell. Therefore, the contrasting behaviour is driven by the stability of the final configuration