### Correct Option: A. CaCO₃ #### Detailed Explanation: 1. **Understanding Smelting in a Blast Furnace**: - Smelting is a process used to extract metal from its ore by heating and melting. In the case of iron, iron ore (primarily composed of iron oxides like Fe₂O₃) is reduced to iron metal in a blast furnace. - The blast furnace operates at high temperatures (around 1500°C) and requires several raw materials to facilitate the reduction of iron ore. 2. **Raw Materials Required**: - The primary raw materials used in the blast furnace include: - **Iron Ore**: The source of iron. - **Coke**: A carbon-rich material derived from coal, which serves as a fuel and reducing agent. - **Limestone (CaCO₃)**: This is where option A comes in. Limestone is added to the furnace to act as a flux. A flux is a substance that helps to remove impurities from the ore. 3. **Role of CaCO₃ (Limestone)**: - When limestone is heated in the blast furnace, it decomposes to form lime (CaO) and carbon dioxide (CO₂): \[ \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2 \uparrow \] - The lime (CaO) then reacts with silica (SiO₂) and other impurities present in the iron ore to form slag (calcium silicate), which can be removed from the furnace. This process helps to purify the iron by removing unwanted materials. 4. **Why Other Options Are Incorrect**: - **B. Zn(NO₃)₂ (Zinc Nitrate)**: - Zinc nitrate is not used in the smelting of iron. It is more relevant in the context of zinc extraction or as a chemical reagent. It does not serve any purpose in the reduction of iron ore or in the formation of slag. - **C. CuSO₄ (Copper(II) Sulfate)**: - Copper sulfate is also not relevant to iron smelting. It is primarily used in agriculture as a fungicide or in chemical reactions involving copper. It does not contribute to the reduction of iron ore or the removal of impurities. - **D. AlCl₃ (Aluminum Chloride)**: - Aluminum chloride is not used in the blast furnace for iron smelting. It is typically used in organic synthesis and as a catalyst in various chemical reactions. It does not play a role in the iron extraction process. 5. **Common Pitfalls**: - Students may confuse the role of different chemicals in metallurgical processes. It’s important to remember that only specific materials like limestone (CaCO₃) are used as fluxes in iron smelting. - Misunderstanding the purpose of the raw materials can lead to incorrect answers. Always consider the chemical reactions involved in the process. ### Revision Summary: - The correct raw material for smelting iron ore in a blast furnace is **CaCO₃ (Limestone)**, which acts as a flux. - Limestone decomposes to form lime (CaO), which helps remove impurities from iron ore. - Other options (Zn(NO₃)₂, CuSO₄, AlCl₃) do not play a role in iron smelting and are used in different chemical contexts. - Understanding the specific roles of materials in metallurgical processes is crucial for answering related questions correctly.