`K_(4)[Fe(CN)_(6)]` can be used to detect one or more out of `Fe^(2+),Fe^(3+),Zn^(2+),Cu^(2+),Ag^(+),Ca^(2+),Th^(4+)`:

Options

A. only `Fe^(2+),Fe^(3+)`
B. only `Fe^(3+),Zn^(2+),Cu^(2+)`
C. all but not `Ca^(2+)`
D. all of these

Answer

D

Explanation

`underset(("White"))(Ag_(4)[Fe(CN)_(6)]darr),underset(("Prussian blue"))(Fe_(4)[Fe(CN)_(6)]_(3)darr)`
`underset(("White ppt turns blue on oxidation"))(K_(2)Fe[Fe(CN)_(6)]darr,)underset(("White ppt of variable composition"))(K_(2)Zn_(3)[Fe(CN)_(6)]_(2)darr)`
`underset(("Chocolate brown ppt"))(Cu_(2)[Fe(CN)_(6)]darr)underset(("White ppt"))(K_(2)Ca[Fe(CN)_(6)]darr)`
`underset(("White ppt"))(Th[Fe(CN)_(6)]darr)`