Problem 122 - A Complete Resource Book in Chemistry for JEE Main

Question

Among the following statements, the incorrect one is (a) calamine and siderite and carbonates (b) argentite and cuprite are oxides (c) zinc blende and pyrites are sulphides (d) malachite and azurite are ores of copper

Step-by-Step Solution

Answer

The incorrect statement is (b), as argentite is a sulphide, not an oxide.

Step 1: Identify Mineral Types in Each Statement

Each of the statements lists minerals and their types. We need to check the mineral class for each. Calamine and siderite are known to be carbonates, so statement (a) is correct. Argentite is a sulphide and Cuprite is an oxide, which makes statement (b) incorrect.

Step 2: Verify the Class of Each Mineral

Zinc blende (ZnS) and pyr(FeS₂) are both sulphides, making statement (c) correct. Malachite and azurite are copper carbonates, which are important ores of copper, validating that statement (d) is correct.

Step 3: Determine the Incorrect Statement

From steps 1 and 2, we find that statements (a), (c), and (d) are correct. Therefore, the incorrect statement is (b) because argentite and cuprite belong to different classes; argentite is a sulphide, not an oxide.

Key Concepts

Mineral Classification

Mineral classification is the process of grouping minerals based on common characteristics such as chemical composition, internal structure, and physical properties. This classification helps geologists and chemists in identifying and studying minerals more effectively. Minerals are categorized primarily based on their chemical makeup and the structure of their crystals.

Some common categories include:

• Silicates: Minerals containing silicon and oxygen.
• Carbonates: Minerals made up of carbonate ions.
• Sulphides: Compounds of sulfur with metals.
• Oxides: Minerals containing metal combined with oxygen.
• Halides: Minerals that contain halogen elements.

Each type of mineral group shares specific properties and characteristics, making it easier for scientists to study them closely and understand their formation and uses.

Carbonate Minerals

Carbonate minerals contain the carbonate ion \( \text{CO}_3^{2-} \). These minerals are significant in geology due to their unique ability to form sedimentary rock through the process of precipitation. They are often soft and may react with acids, leading to effervescence.

Common carbonate minerals include:

• Calcite: Known for forming limestone and marble.
• Dolomite: Used in construction materials.
• Siderite and Magnesite: Important iron and magnesium sources, respectively.
• Malachite and Azurite: Notable for their vibrant blue and green colors, these are secondary copper ores.

Understanding carbonate minerals is crucial for various applications in building materials, industrial processes, and even ancient historical research due to their widespread use and presence in archaeological sites.

Sulphide Minerals

Sulphide minerals consist of sulfur combined with one or more metals or semimetals. These minerals are primarily known as ores from which metals are extracted. They usually appear as metallic-looking minerals and are often valuable due to the metals they contain.

Examples of sulphide minerals include:

• Pyrite: Often referred to as 'fool's gold,' it forms striking golden crystals.
• Galena: A primary source of lead.
• Chalcopyrite: A key copper ore known for its brassy yellow color.
• Argentite: A significant silver ore.

Sulphide minerals are critical to the mining industry and are extensively used in the production of various metal commodities. Their study is important not only for resource extraction but also for understanding geochemical processes.

Copper Ores

Copper ores are types of rock that contain copper minerals in commercially viable amounts. These ores are the primary sources of copper for industrial extraction and are crucial to modern technologies and construction.

Significant copper ores include:

• Chalcopyrite: The most abundant copper ore.
• Bornite: Known as 'peacock ore' for its iridescent colors.
• Copper Carbonates: Malachite and azurite, known for their striking green and blue hues, respectively.
• Copper Oxides: Cuprite and tenorite, which are also key sources.

Copper is essential for electrical wiring, plumbing, and the manufacture of electronics, making the understanding and extraction of copper ores a vital industry. Exploration and development in copper mining continue to be necessary to meet global demand.