Explain why Cr2+ is reducing but Mn3+ is oxidising while both ions have d4 configuration?
Cr2+ is reducing in nature. It had a d4 configuration. While acting as a reducing agent,it gets oxidized to Cr3+ which has electronic configuration d3 . This d3 configuration Can be written as t2g to the power of 3 which is a more stable configuration
In case of Mn3+ which is a n oxidising agent gets reduced to Mn2+ . This has an exactly half filled d orbital and is highly stable
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