Question

`K_4 [Fe(CN)_6]` can be used to detect one or more out of `Fe^(2+), Fe^(3+), Zn^(2+), Cu^(2+), Cd^(2+)`
A. `Fe^(2+),Fe^(3+)`
B. `Fe^(3+),Zn^(2+),Cu^(2+)`
C. All but `Fe^(3+)`
D. All but `Fe^(2+)`

Answer 1

`2ZnCl_(2) +K_(4)[Fe(CN)_(6)] overset(CH_(3)CO OH)to underset("(Prussian blue)")underset("Ferric ferrocyanide")(Fe_(4)[Fe(CN)_(6)]_(3)+12KCl`
`2Cu(NO_(3))_(2) + K_(4)[Fe(CN)_(6)] to underset("(Reddish brown)")(Cu_(2)[Fe(CN)_(6)])+4KNO_(3)`
`2Cd(NO_(3))_(2)+K_(4)[Fe(CN)_(6)] to underset("(Bluish white)")(Cd_(2)[Fe(CN)_(6)])+4KNO_(3)`