Question

The eo valures for mn and zn are more negative than expected because

Answer 1

Negative values of ${{Mn}^{2+}}$ and ${{Zn}^{2+}}$ are related to stabilities of half-filled and completely filled configuration respectively. But for ${{Ni}^{2+}}$, E° value is related to the highest negative enthalpy of hydration.

Hence, E° values of Mn, Ni and Zn are more negative than expected.