Q1: Which of the following is capable of acting both as an acid flux as well as a basic flux in the metal extraction from its ore ?

ANS:C - Alumina

Alumina, also known as aluminum oxide (Al2O3), is a compound commonly found in nature as the mineral corundum. Here's an explanation of alumina:

1. Chemical Composition: Alumina is composed of two atoms of aluminum (Al) and three atoms of oxygen (O), with a chemical formula of Al2O3.
2. Physical Properties:
   • Alumina is a white, crystalline solid with a high melting point of approximately 2,072°C (3,762°F).
   • It is relatively inert chemically and is insoluble in water.
   • Alumina is very hard and is often used as an abrasive material in applications such as sandpaper, grinding wheels, and cutting tools.
3. Applications:
   • Refractory Material: Alumina is widely used as a refractory material due to its high melting point and excellent thermal stability. It is used in the production of refractory bricks, crucibles, and linings for furnaces and kilns.
   • Aluminum Production: Alumina is the primary source of aluminum metal. It is extracted from bauxite ore through the Bayer process, which involves dissolving bauxite in sodium hydroxide (NaOH) solution to produce aluminum hydroxide, which is then calcined to produce alumina. Alumina is subsequently electrolyzed to produce aluminum metal.
   • Ceramic Industry: Alumina is used extensively in the ceramic industry as a raw material for the production of ceramic products such as tiles, pottery, and porcelain.
   • Catalyst Support: Alumina is used as a support material for catalysts in various chemical processes. Its high surface area and stability make it suitable for supporting catalytic metals and promoting chemical reactions.
   • Abrasive Material: Due to its hardness, alumina is used as an abrasive material in sandpapers, grinding wheels, and polishing compounds for metalworking, woodworking, and surface finishing applications.
4. Other Uses:
   • Alumina is used in the production of aluminum metal, which finds extensive applications in various industries, including aerospace, automotive, construction, and packaging.
   • It is also used in the manufacture of electrical insulators, spark plugs, and heat-resistant ceramics.