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.

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

Cations and anions [formation from an atom]

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.

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.