State the reason for addition of caustic alkali to bauxite ore .
WEBQ. Aluminium is extracted from its chief ore, bauxite. The ore is first purified and then the metal is extracted from it by electrolytic reduction. (a) Write three balanced equations for the purifiion of bauxite by Hall's process. (b) Name a chemical used for dissolving aluminium oxide. In which state of subdivision is the chemical used?