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The D-And-f-Block Elements

Question
CBSEENCH12010748

The correct order of E°M2+/M values with negative sign for the four successive elements Cr, Mn, Fe and Co is

  • Cr > Mn > Fe > Co

  • Mn > Cr > Fe > Co

  • Cr > Fe > Mn > Co

  •  Fe > Mn > Cr > Co

Solution

B.

Mn > Cr > Fe > Co

Across the first transition series, the negative values for standard electrode potential decrease except for Mn due to the stable d5 configuration.
Mn > Cr > Fe > Co