JAMB - Chemistry (2002 - No. 23)
The gas that gives brown colouration in brown ring test is
NO
CO2
NO2
CO
הֶסבֵּר
In the brown ring test, nitric oxide (NO) is produced when acidified iron (II) sulphate reacts with dilute nitric acid. The nitric oxide then reacts with iron (II) to form a complex ion, which creates a brown ring at the junction of the two liquids.