The reaction given below
\([Fe^*(CN)_6]^{4-} +[Fe(CN)_6]^{3-} \to [Fe^*(CN)_6]^{3-} + [Fe(CN)_6]^{4-}\)
takes place by the
1
inner-sphere mechanism mediated by the CN- bridge
2
outer-sphere mechanism mediated by the CN- bridge
3
inner-sphere mechanism with no net chemical change
4
outer-sphere mechanism with no net chemical change