p-Amino-N,N-dimethylaniline is added to a strongly acidic solution of X. The resulting solution is treated with a few drops of aqueous solution of Y to yield blue colouration due to the formation of methylene blue. Treatment of aqueous solution of Y with reagent potassium hexacyanoferrate (II) leads to the formation of an intense blue precipitate. The precipitate dissolves on excess addition of the reagent. Similarly, the treatment of the solution of Y with the solution of potassium hexacyanoferrate (III) leads to a brown colouration due to the formation of Z.
Q. Compound Z is

Options

A. `Mg_(2)[Fe(CN)_(6)]`
B. `Fe[Fe(CN)_(6)]`
C. `Fe_(4)[Fe(CN)_(6)]_(3)`
D. `K_(2)Zn_(3)[Fe(CN)_(6)]_(2)`

Answer

B

Explanation

`Fe^(3+)+[Fe(CN)_(6)]^(3-)rarrFe[Fe(CN)_(6)]`
(brown colouration)(Z).