JEE Main 2026 — p Block Elements (Group 15, 16, 17 & 18) Question with Solution

The brown ring test is used for the detection of nitrate (${\text{NO}}_3^{-}$) or nitrite (${\text{NO}}_2^{-}$) ions.

In this test, nitric oxide (NO) gas is evolved which reacts with the freshly prepared ferrous sulphate (${\text{FeSO}}_4$) solution to form a brown ring of nitroso ferrous sulphate.

The gas $X$ is NO.

The reaction is given by:

${\text{FeSO}}_4+\text{NO}\to [\text{Fe(NO)}]{\text{SO}}_4$

The actual composition of the brown ring complex is $[{\text{Fe(H}}_2\text{O}{)}_5(\text{NO})]{\text{SO}}_4$, which is often represented as $[\text{Fe(NO)}]{\text{SO}}_4$.

Thus, $X$ is NO and $Y$ is $[\text{Fe(NO)}]{\text{SO}}_4$.

Answer: NO and $[\text{Fe(NO)}]{\text{SO}}_4$