When salt solution 'A' is added carefully to a saturated solution of Fe(II) sulphate acidified With dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$a brown ring is formed at the junction of two liquids. Salt 'A' may be :

At the intersection of two layers—the first layer being a combination of iron sulphate solution and sample solution, and the second layer being a concentrated sulphuric acid solution—a brown ring forms.

Nitrate is present in the sample, as shown by the brown ring.

Reactions to the Brown Ring Test

The following responses occur during the brown ring test:

$\begin{array}{l}2{\mathrm{HNO}}_3+3{\mathrm{H}}_2{\mathrm{SO}}_4+6{\mathrm{FeSO}}_4\to 3{\mathrm{Fe}}_2{\left({\mathrm{SO}}_4\right)}_3+\mathrm{NO}+4{\mathrm{H}}_2\mathrm{O}\\ \left(\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right){\mathrm{SO}}_4+\mathrm{NO}\to \left(\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_5\mathrm{NO}\right){\mathrm{SO}}_4+{\mathrm{H}}_2\mathrm{O}\end{array}$

Where, a nitrosyl compound of  $\left(\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_5\mathrm{NO}\right){\mathrm{SO}}_4$ is shown

Correct option is B