When concentrated sulphuric acid is added slowly to a solution of ferrous sulphate containing nitrate ion, a brown colour ring is formed. The compositionn of the ring is

Options

A. `[Fe(H_(2) O_(2))_(5) NO]SO_(4)`
B. `FeSO_(4). NO_(2)`
C. `Fe [H_(2) O)_(5)] (NO_(3))_(2)`
D. None of these

Answer

A

Explanation

`NO_(3)^(-) + H_(2) SO_(4) rarr HNO_(3) + HSO_(4)^(-)`
`2HNO_(3) rarr H_(2)O + 2NO + 3 [O]`
`FeSO_(4) + NO + 5H_(2) O rarr underset(("Prussian blue"))underset("Ferric ferrocyanide")([Fe(H_(2) O)_(5) NO^(+)] SO_(4)) `