In the ring test of `NO_(3)^(-)` ion, `Fe^(2+)` ion reduces nitrate ion to nitric oxide, which combines with `Fe^(2+)` (aq) ion to form brown complex .
Write the reactions involved in the formation of brown ring.

Explanation

`NO_(3)^(-)+3Fe^(2+)+4H^(+)toNO+3Fe^(3+)+2H_(2)O`
`[Fe(H_(2)O)_(6)]^(2+)+NOtounderset("Brown ring")([Fe(H_(2)O)_(5)NO]^(2+))+H_(2)O`
This test is known as brown ring test of nitrates generally used to identify the presence of nitrate ion given solution.