Differentiate between the following pairs based on the information given in the bracket.

Cations and anions [formation from an atom]

State one relevant observation for the reaction : Sulphide ore is added to a tank containing oil and water and then stirred or agitated with air.

Give one word or a phrase for the statement : The substance prepared by adding other metals to a base metal in appropriate proportions to obtain certain desirable properties.

Baeyer's process is used to concentrate bauxite ore to alumina. Give balanced chemical equations for the reaction taking place for it's conversion from bauxite to alumina.