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.

Answer the following questions based on the extraction of aluminium from alumina by Hall- Heroult's Process.

(i) What is the function of cryolite used along with alumina as the electrolyte.

(ii) Why is the powdered coke sprinkled on top of the electrolyte.

(iii) Name the electrode from which aluminium is collected.

Match the alloys given in column I with the uses given in column II

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.