The correct option is **C. tin**. ### Detailed Explanation: 1. **Understanding Cassiterite**: - Cassiterite is a mineral composed primarily of tin dioxide (SnO2). It is the most significant ore of tin and is found in various geological environments, often associated with granite and other igneous rocks. - The chemical formula indicates that cassiterite contains tin (Sn) in a stable oxide form, which is crucial for its extraction. 2. **Extraction Process**: - The extraction of tin from cassiterite typically involves a process called smelting. In this process, cassiterite is heated with carbon (often in the form of coke) in a furnace. The carbon reduces the tin oxide to metallic tin. - The reaction can be summarized as follows: \[ \text{SnO}_2 + 2\text{C} \rightarrow \text{Sn} + 2\text{CO} \] - This reaction shows that tin is liberated from its oxide form, allowing it to be collected as a pure metal. 3. **Why Other Options Are Incorrect**: - **A. Calcium**: Calcium is not extracted from cassiterite. It is typically obtained from minerals like limestone (calcium carbonate) or gypsum (calcium sulfate). The extraction process for calcium involves different methods, such as electrolysis or thermal reduction, which are not applicable to cassiterite. - **B. Magnesium**: Magnesium is primarily extracted from minerals like dolomite (calcium magnesium carbonate) or magnesite (magnesium carbonate). The extraction methods involve different chemical processes, such as the Pidgeon process or electrolysis, which do not relate to cassiterite. - **D. Copper**: Copper is extracted from ores such as chalcopyrite (CuFeS2) or malachite (CuCO3·Cu(OH)2). The extraction of copper involves processes like roasting and smelting, which are entirely different from the processes used for extracting tin from cassiterite. ### Common Pitfalls: - Students may confuse the extraction processes of different metals and their respective ores. It is essential to remember that each metal has specific ores from which it is economically viable to extract. - Misunderstanding the chemical formulas of minerals can lead to incorrect answers. Knowing the composition of cassiterite (SnO2) is crucial for identifying that it is a source of tin. ### Revision Summary: - Cassiterite is the primary ore of tin, composed of tin dioxide (SnO2). - Tin is extracted from cassiterite through smelting, reducing the oxide to metallic tin. - Other options (calcium, magnesium, copper) are derived from different minerals and extraction processes. - Understanding the specific ores and extraction methods for each metal is vital for success in chemistry exams.