Question

A brown ring appears in the test for

• A.
  Nitrate
• B.
  Nitrite
• C.
  Bromide
• D.
  Iron

Answer 1

The correct option is A

Nitrate
Brown ring test is a chemical test carried out to detect the presence of nitrate ions.The brown ring test or nitrate test is a reduction reaction. The nitrate is reduced to nitric oxide by ferrous (II), which is oxidized to ferrous (III).
$N{O}_3^{-}+3F{e}^{2+}+4H^{+}⟶NO+3F{e}^{3+}+2H_{2}O\left[Fe\right(H_{2}O{)}_6{]}^2++NO⟶\left[Fe\right(H_{2}O{)}_{5}NO{]}^{2+}+H_{2}OBrownring$