Write the role of the following:

(i) Iodine in the refining of zirconium.

(ii) Silica in the extraction of copper from copper matte.

Zirconium reacts with iodine to form volatile compound ZrI₄. These vapours are decomposed to give pure zirconium and iodine gas, which is allowed to escape leaving behind pure zirconium.

(ii) Silica is used to remove iron oxide from copper matte. When silica is added to copper ore containing iron oxide, silica reacts with iron oxide to give iron silicate(FeSiO₃) which is removed as slag.