Cations (Zn(II), Al(III), Cu(II), Fe(II) and Fe(III): Tested with NaOH.

Must see: My new website at ww.acechemistry....
Sodium hydroxide is added slowly and then in excess to solutions of these salts.
The zinc (II) and Aluminium (III) form white gelatinous hydroxide precipitates that redissolve. Copper (II) forms a light blue hydroxide that does not disssolve. Iron (II) and (III), respectively, form green and brown hydroxides that do not redissolve.