When a reagent (X) reacts with `Fe^(3+)` salt solution turnsred due to the formation of a compound (Y). This reagent cause no change in colour with `Fe^(2+)` salt solution. Compound (X) and (Y) are respectively:

Options

A. `NH_(4)SCN and Fe(SCN)_(3)`
B. `K_(4)[Fe(CN)_(6)] and FeSO_(4)`
C. `Na_(2)HPO_(4) and FeSO_(4)`
D. `K_(3)[Fe(CN)_(6)] and K_(2)Fe[Fe(CN)_(6)]`

Answer

A

Explanation

`Fe^(3+)+underset((X))(3NH_(4)SCN) to 3NH_(4)^(+) +underset(("blood red colour solution")(Y))(Fe(SCN)_(3))`
`NH_(4)SCN` has no change in colour with `Fe^(2+)`.