Question

The correct order of $Eº_{M^{2 +}/M}$ values with negative sign for the four successive elements Cr. Mn, Fe and Co is

• A. Fe>Mn>Cr>Co
• B. Cr>Mn>Fe>Co
• C. Mn>Cr>Fe>Co
• D. Cr>Fe>Mn>Co

Answer 1

Answer: (C)

Mn>Cr>Fe>Co

Answer 2

$Eº$ values for $M^{2 +}/M$ with negative signs are $Cr = - 0.91V,Mn = - 1.18V,Fe = - 0.44V,Co = - 0.28V$thus the order is $Mn > Cr > Fe > Co$