The formation of brown ring in the reaction between nitrates, conc. `H_2SO_4` and `FeSO_4` involves

Options

A. oxidation of nitric oxide to nitrogen dioxide
B. reduction of ferrous sulphate to iron
C. reduction of nitrate to nitric oxide
D. oxidising property of sulphuric acid

Answer

C

Explanation

`Fe^(2+)` ion has a tendency to reduce `NO_3^- ` to nitric oxide NO `(N^(2+))` in presence of conc. `H_2SO_4`.
`NO_3^(-) + 3Fe^(2+) + 4H^(+) to NO+ 3Fe^(3+) + 3H_2O`