The formula for iron (III) hexacyanoferrate(II), commonly known as Prussian blue, is
1. `Fe_3[Fe(CN)_6]_2`
2. `Fe_2[Fe(CN)_6]_3`
3.`Fe_4[Fe(CN)_6]_3`
4.`Fe_3[Fe(CN)_6]_4`

In K_4Fe(CN)_6

K_(3)[Fe(CN)_(6)]+FeCl_(3) to Fe[Fe(CN)_(6)]

FeCl_3 + K_4[Fe(CN)_6] to ?

K_(3)[Fe(CN)_(6)]+FeCl_(2) to Fe_(3)[Fe(CN)_(6)]_(2)darr

3KCN+Fe(CN)_(3)darr to K_(3)[Fe(CN)_(6)]

Oxidation state of Fe in K_3[Fe(CN)_6] is

In the Lassaigne’s test for nitrogen in an organic compound, the Prussian blue colour is obtained due to the formation of: (a) Na_(4)[Fe(CN)_(6)] (b) Fe_(4)[Fe(CN)_(6)]_(3) (c) Fe_(2)[Fe(CN)_(6)] (d) Fe_(3)[Fe(CN)_(6)]_(4)