When dilute ferrous sulphate solution is added lto an aqueous solution containing nitrate ion followed by careful addition of concentrated sulphuric acid along the sides of test tube a ,brown ring is formed at the iterface between the solution and sulphuric acid layers .Which is anion is confined by the appearance of brown ring .What the conposition of the brown ring ?

Explanation

A brown ring wall from at the junction of the two layers ,indicting the presence of nitrate ion.The brown ring formed in the confirmatory test for the nitrate ion is due to the complex called nitros ferrous sulphate with the formula `[Fe(H_2O)_5(NO)]SO_4`