Coordination compounds related doubt

Question

In which of the following compounds iron has lowest oxidation number?
(1) FeSO4 · (NH4) 2SO4 · 6H2O
(2) K4[Fe(CN)6]
(3) Fe2O
(4) Fe2O3

Answer 1

(1) FeSO4 · (NH4) 2SO4 · 6H2O  Fe = 2+
(2) K4[Fe(CN)6]  Fe =2+
(3) Fe2O  Fe = 1+
(4) Fe2O3  Fe = 3+

 

So, Fe would have the lowest oxidation number in Fe2O where is is 1+