Name the process by which impure ore of aluminium gets purified by using concentrated solution of an alkali.

Bayer's process is the process used for the purification of the impure ore of aluminium using concentrated solution of an alkali. In this process, finely powdered ore is treated with hot solution of sodium hydroxide.

Name the most common ore of the metal aluminium from which the metal is extracted. Write the chemical formula of the ore.

The most common ore of aluminium is the bauxite. It is an oxide ore. Bayer's process is used to obtain pure aluminium oxide from the bauxite ore. The chemical formula is A l 2 O 3 . The metal is extracted from this ore using the process called Hall-Heroult's process which involves the process of electrolysis.