• # question_answer In the qualitative analysis of nitrate a brown ring is formed due to the formation of [AMU 2001] A) $N{{O}_{2}}$ B) $FeS{{O}_{4}}N{{O}_{2}}$ C) ${{N}_{2}}O.FeS{{O}_{4}}$ D) $FeS{{O}_{4}}.NO$

Nitrates on reaction with conc. ${{H}_{2}}S{{O}_{4}}$ and $FeS{{O}_{4}}$ give a brown ring due to formation of $FeS{{O}_{4}}.NO$ or  $[Fe{{({{H}_{2}}O)}_{5}}NO]S{{O}_{4}}$.