The correct option is **B. Sand**. ### Explanation of the Correct Answer **Filtration Process:** Filtration is a physical separation method used to separate solids from liquids or gases using a filter medium that allows only the fluid to pass through while retaining the solid particles. In this case, we are looking to separate sodium chloride (NaCl) from an aqueous mixture that contains another component. **Understanding the Components:** 1. **Sodium Chloride (NaCl)**: This is a soluble salt that dissolves in water to form a solution of sodium ions (Na⁺) and chloride ions (Cl⁻). 2. **Sand**: Sand is an insoluble solid that does not dissolve in water. It remains as a solid particle in the mixture. **Filtration of the Mixture:** When you perform filtration on a mixture of sodium chloride and sand: - The **aqueous solution** containing dissolved sodium chloride will pass through the filter paper. - The **sand**, being insoluble, will be retained on the filter paper. Thus, by using filtration, you can obtain a pure solution of sodium chloride in the filtrate (the liquid that passes through) while the sand remains on the filter paper. ### Why the Other Options are Incorrect **A. Potassium Nitrate (KNO₃)**: - Potassium nitrate is also a soluble salt, similar to sodium chloride. When mixed with water, it dissolves to form potassium ions (K⁺) and nitrate ions (NO₃⁻). - If you attempted to filter a mixture of sodium chloride and potassium nitrate, both salts would pass through the filter paper as they are both soluble in water. Therefore, you would not be able to separate sodium chloride from potassium nitrate using filtration. **C. Lead Nitrate (Pb(NO₃)₂)**: - Lead nitrate is another soluble salt. Like potassium nitrate, it dissolves in water to form lead ions (Pb²⁺) and nitrate ions (NO₃⁻). - Similar to the previous case, if you mixed sodium chloride with lead nitrate in water, both would dissolve and pass through the filter paper, making it impossible to separate them by filtration. **D. Sugar (Glucose)**: - Sugar (glucose) is also soluble in water. When mixed with sodium chloride in an aqueous solution, both substances will dissolve. - Therefore, filtration would not work to separate sodium chloride from sugar, as both would be present in the filtrate. ### Summary of Key Points - **Filtration** is effective for separating insoluble solids from liquids. - **Sodium chloride** is soluble in water, while **sand** is not, allowing for effective separation. - Other options (potassium nitrate, lead nitrate, and sugar) are all soluble in water, making them unsuitable for separation by filtration. - Understanding the solubility of substances is crucial for choosing the right separation technique. ### Revision Summary - Filtration separates insoluble solids from liquids. - Sodium chloride is soluble; sand is not, allowing for separation. - Potassium nitrate, lead nitrate, and sugar are all soluble, making them ineffective for filtration separation from sodium chloride. - Always consider the solubility of components when selecting a separation method.