Q1: Which of the following is not an ore of copper?

ANS:A - Cryolite

Cryolite is a mineral with the chemical formula Na₃AlF₆. It is a rare and naturally occurring fluoride mineral that crystallizes in the monoclinic crystal system. Cryolite is typically colorless, white, or gray, but it may also appear in shades of blue or green due to impurities. Here are some key characteristics and uses of cryolite:

1. Occurrence: Cryolite was originally found in large deposits in Greenland, where it was mined extensively for commercial use. However, natural deposits of cryolite are now relatively scarce, and most of the cryolite used today is synthetic.
2. Synthetic Production: Due to its scarcity in nature, cryolite is primarily produced synthetically for industrial applications. The synthetic production process involves the reaction of sodium fluoride (NaF) and aluminum fluoride (AlF₃) in the presence of aluminum oxide (Al₂O₃).
3. Industrial Applications: Cryolite has several industrial applications, the most significant of which is its use in the production of aluminum. It serves as a flux in the electrolytic reduction of alumina (aluminum oxide) to aluminum metal in the Hall-Héroult process. Cryolite helps lower the melting point of alumina and increases its conductivity, making the aluminum extraction process more energy-efficient.
4. Other Uses: In addition to its role in aluminum production, cryolite is also used in the manufacturing of ceramics, glass, and enamel. It can act as a flux in ceramic and glass formulations, helping to lower the melting point and improve the flow properties of the materials.
5. Historical Significance: Cryolite played a significant role in the development of the aluminum industry during the late 19th and early 20th centuries. The discovery of large natural deposits of cryolite in Greenland facilitated the commercial production of aluminum, leading to the widespread use of aluminum in various industries.

Overall, cryolite is an important industrial mineral with a range of applications, particularly in the production of aluminum and in ceramic and glass manufacturing. While natural deposits of cryolite are rare, its synthetic production has ensured its continued availability for industrial use.