Consider the following experiments and answer the questions at the end of it
(A) When `Fe(CN)_(2)` solution is treated with `KCN` solution species formed no longer gives tests of `Fe^(2+)` and `CN^(Θ)`
(B) When `K_(2)SO_(4)` solution is treated with `A1_(2)(SO_(4))_(3)` solution species formed gives tests of `K^(o+),A1^(3+)` and `SO_(4)^(2-)`
Species formed in experiment `A` does not give test of `Fe^(2+)` and `CN^(Θ)` it is due to formation of .

Options

A. `K_(2)[Fe(CN)_(4)]`
B. `K_(3)[Fe(CN)_(5)]`
C. `K_(3)[Fe(CN)_(6)]`
D. `K_(4)[Fe(CN)_(6)]`

Answer

D

Explanation

`Fe(CN)_(2)+4KCNrarrK_(4)[Fe(CN)_(6)]`
(Complex compounds)