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Q.
In the brown ring test, the brown colour of the ring is due to
Chhattisgarh PMTChhattisgarh PMT 2011
Solution:
To the nitrate salt, add freshly prepared $FeSO _{4}$ solution and then cone.
$H _{2} SO _{4}$ $H _{2} SO _{4}$ carefully by the sides of test-tube.
A dark brown ring of ferrous nitroso sulphate is formed.
$NaNO _{3}+ H _{2} SO _{4} \rightarrow NaHSO _{4}+ HNO _{3}$
$2 HNO _{3}+6 FeSO _{4}+3 H _{2} SO _{4} \rightarrow 3 Fe _{2}\left( SO _{4}\right)_{3}+2 n o+4 H _{2} O$
$FeSO _{4}+ NO \rightarrow \underset{\text{ferrous nitrososulphate (brown ring)}}{[FeNO] SO _{4}}$