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_2Zn_3[Fe(CN)_6]_2`

Answer

B

Explanation

`4FeCl_3+3K_4[Fe^(2+)(CN)_6]toFe_4[Fe(CN)_6]_3+2KCl`
`FeCl_3+K_3[Fe^(3+)(CN)_6]toFe[Fe(CN)_6]+3KCl`