JAMB - Chemistry (2011 - No. 30)
A few drops of concentrated HNO\(_3\) is added to an unknown solution and boiled for a while. If this produces a brown solution, the cation present is likely to be
Pb2+
Cu2+
Fe3+
Fe2+
解释
The brown color indicates the presence of iron (III) (Fe\(^{3+}\)).