Brown ring test is performed for the qualitative detection of :

 

The brown ring test is used to identify nitrates qualitatively.

When the solid chloride is combined with manganese dioxide and heated, a brown yellowish-green gas of chlorine with a suffocating odour is released.

Iron(II) sulphate is added to a solution containing nitrate ions to conduct a ring test. Then, add strong sulphuric acid slowly and carefully without stirring the mixture to create a layer of sulphuric acid underneath the aqueous solution. At the intersection of the two layers,  $\left[\mathrm{Fe}\right(\mathrm{H}2\mathrm{O}{)}_5\mathrm{NO}]{\mathrm{SO}}_4$ will produce a  brown ring if nitrate is present.