Question

The brown ring test for nitrates depends on 1) reduction of ferrous sulphate to iron 2) oxidation of nitric oxide to nitrogen dioxide 3) the reduction of nitrate to nitric oxide 4) oxidising action of sulphuric acid

Answer 1

The answer's 3, do you need the whole explanation?

Answer 2

The brown ring test is the commonest method of testing for nitrates

The elements involved in the test is the iron (II) sulphate and the nitrate solution and sulphuric acid .it is performrd by adding iron (II)sulphate to a solution nitrate ,sulphuric acid is then added so that it forms a layer below the aqueous solution .

It is noted that a brown ring forms between the two solutions