The Quest for the Carbonate Group
In the fascinating world of metallurgy, identifying the correct ore is the very first step toward extracting a pure metal. This question presents us with a classic lineup of suspects and asks us a simple yet crucial question: Which of these is NOT a carbonate ore?
To solve this, we need to recall what makes an ore a "carbonate" ore. Simply put, a carbonate ore must contain the carbonate anion, which is chemically represented as CO32−. Our mission is to interrogate the chemical formula of each option and see if the carbonate group is hiding inside.
Interrogating the Suspects
Let's bring our suspects to the stand one by one:
1. Siderite: This is a well-known ore of iron. Its chemical formula is FeCO3. As we can clearly see, the CO3 group is right there. Siderite is definitely a carbonate ore.
2. Calamine: This is an important ore of zinc. Its chemical formula is ZnCO3. Once again, the carbonate group is present. Calamine is also a carbonate ore.
3. Malachite: This beautiful green ore is a source of copper. Its formula is a bit more complex: CuCO3⋅Cu(OH)2. It is technically a basic carbonate ore because it contains both carbonate and hydroxide groups. However, since the CO3 group is present, it qualifies as a carbonate ore for our classification.
The Odd One Out
Finally, we arrive at Bauxite. Bauxite is the primary commercial ore of aluminium. If we recall its chemical composition, it is a hydrated aluminium oxide. Its general formula is written as Al2O3⋅xH2O (or sometimes as AlOx(OH)3−2x).
Do you see a CO3 group anywhere in that formula? Absolutely not! Bauxite is an oxide ore, not a carbonate ore.
The Final Verdict
By systematically checking the chemical formulas, we have successfully unmasked the imposter. Bauxite is the only ore in the given list that does not contain a carbonate group.
Questions like these are highly scoring in competitive exams like JEE. They test your direct memory of fundamental chemical facts. Make sure you have a solid grip on the common ores of important metals like Iron, Copper, Zinc, and Aluminium!