Which of the following has least oxidation state of Fe?

Options

A. `K_3[Fe(OH)_6]`
B. `K_2[FeO_4]`
C. `FeSO_4.(NH_4)_2SO_4.6H_2O`
D. `[Fe(CN)_6]^(3-)`

Answer

C

Explanation

In mohr salt `FeSO_4. (NH_4)_2 SO_4.6H_2O`, oxidation state of iron is +2 which is least.
`{:(K_3[Fe(OH)_6],+3+x-6=0,x = +3),(K_2[FeO_4],+2+x-8=0,x = +6),(FeSO_4.(NH_4)_2SO_4. 6H_2O,+2 "state in " FeSO_4,(x-2=0)),(Fe(CN)_6^(3-),x-6=-3,x=+3):}`