Ferrous sulphate gives a dirty green precipitate with sodium hydroxide.
Action of Alkalis — on oxides and hydroxides of certain metals
| Zinc oxide | ZnO + NaOH ⟶ ____ + ____ |
| Zinc hydroxide | Zn(OH)2 + NaOH ⟶ ____ + ____ |
| Lead [II] oxide | PbO + NaOH ⟶ ____ + ____ |
| Lead hydroxide | Pb(OH)2 + NaOH ⟶ ____ + ____ |
| Aluminium oxide | Al2O3 + NaOH ⟶ ____ + ____ |
| Aluminium hydroxide | Al(OH)3 + KOH ⟶ ____ + ____ |