The  ${\mathrm{E}}_{{\mathrm{M}}^{+3}|{\mathrm{M}}^{+2}}^0$  values for Cr, Mn, Fe and Co are – 0.41, + 1.57V, + 0.77 and + 1.97V respectively. For wihch one of these metals the change in oxidation sate 

from + 2 to + 3 is easiest?

• A

  Co   

• B

  Mn

• C

   Fe

• D

  Cr