Four successivemembers of the first row transition elementsare listedbelow with atomic numbers. Which one of themis expected to have the highest E_(M^(3+) //M^(2+))^(@)value ?

Four successivemembers of the first row transition elementsare listedb

1.	Four successivemembers of the first row transition elementsare listedbelow with atomic numbers. Which one of themis expected to have the highest E_(M^(3+) //M^(2+))^(@)value ?
Answer» `CO(Z= 27)` `Cr(Z= 24)` `MN(Z=25)` `Fe(Z= 26)` Solution :Highest `E_(M^(3+) //M^(2+))^(@)` value means highest reduction potentialincreases from leftto rightalong the period in d-block but there are some exceptions. `Cr^(3+)` is more stable than `Cr^(2+)`. `Fe^(3+)(3D^(5))` is morestable than `Fe^(3+)` but `Mn^(2+)(3d^(5))` is more stable than `Mn^(3+)` but `Co^(2+)` ionsare still more stable than `Co^(3+)` in AQUEOUS solution as`Co^(3+)` are easily reduced to`Co^(2+)` by `H_(2)O` . Hence, `Co^(3+) // Co^(2+)` has highest reduction potential `(E_(Cr^(3+)//Cr^(2+))^(@)= -0.41V, E_(Mn^(3+ ) //Mn^(2+))^(@)= + 1.57V,E_(Fe^(3+) //Fe^(2+))^(@)= + 0.77V, E_(Co^(3+) //Co^(2+))^(@)=1.97V)`