Which of the following metal(s) is (are) extracted by self-reduction process?CuAlHgPb

The metals that are extracted by the self-reduction process are Copper (Cu) and Mercury (Hg).

Here's a step-by-step explanation:

1. Self-reduction process, also known as auto-reduction, involves the reduction of ores to a metal by heating the ore in a limited supply of air so that it partially roasts and partially reduces.

2. Copper (Cu) is extracted by self-reduction process. The ores of copper are heated in a reverberatory furnace. If air is not supplied, then the ore gets heated in its closed furnace. The moisture in the ore gets evaporated. Due to the heat and removal of moisture, the ore becomes porous where the sulphur content in the ore, reacts with the oxygen to form SO2 and the copper present in the ore gets reduced.

3. Mercury (Hg) is also extracted by a similar process. In this case, the ore is first roasted in air to produce mercuric oxide. Further heating then results in self-reduction, producing pure mercury.

4. Aluminium (Al) and Lead (Pb) are not extracted by the self-reduction process. Aluminium is usually extracted by the Hall-Heroult process, which involves electrolytic reduction. Lead is usually extracted by roasting the ore in air first to convert it to lead(II) oxide, then heating in a blast furnace with carbon to remove the oxygen, leaving pure lead.