The correct option for separating a mixture of oil and water is **D. Liquid-liquid extraction**. ### Detailed Explanation 1. **Understanding the Mixture**: - Oil and water are two immiscible liquids, meaning they do not mix. When combined, they form two distinct layers: oil (which is less dense) floats on top of water (which is denser). This property is crucial for selecting the appropriate separation technique. 2. **Why Liquid-Liquid Extraction?**: - **Principle**: Liquid-liquid extraction is based on the difference in solubility of compounds in two different immiscible liquids. In this case, oil and water are the two phases. - **Process**: In liquid-liquid extraction, a solvent (which can be another liquid) is added to the mixture. The solvent selectively dissolves one of the components (either oil or water) while leaving the other behind. This allows for the separation of the two liquids. - **Efficiency**: This method is particularly effective for separating components based on their different polarities. Since oil is non-polar and water is polar, they can be effectively separated using this technique. 3. **Why the Other Options Are Incorrect**: - **A. Filtration**: - Filtration is used to separate solids from liquids or gases using a porous barrier. Since both oil and water are liquids, filtration would not be effective in separating them. It is designed for heterogeneous mixtures where solid particles can be trapped. - **B. Distillation**: - Distillation is a technique used to separate components of a mixture based on differences in boiling points. While it can separate some liquid mixtures, oil and water have significantly different boiling points (water boils at 100°C, while many oils have higher boiling points). However, distillation is not the best choice here because it is more suited for separating miscible liquids or purifying a single liquid rather than separating two immiscible liquids. - **C. Centrifugation**: - Centrifugation involves spinning a mixture at high speeds to separate components based on density. While it can separate immiscible liquids, it is generally more complex and less efficient for simple separations like oil and water compared to liquid-liquid extraction. It is often used for biological samples or when dealing with small volumes. ### Summary of Key Points - **Liquid-liquid extraction** is the most suitable method for separating oil and water due to their immiscibility and differing polarities. - **Filtration** is ineffective for liquid-liquid mixtures. - **Distillation** is not ideal for immiscible liquids and is better for miscible liquids or purifying a single component. - **Centrifugation** can separate immiscible liquids but is more complex and less efficient for this specific case. ### Revision Summary - Oil and water are immiscible liquids, making them suitable for separation by liquid-liquid extraction. - Liquid-liquid extraction utilizes differences in solubility and polarity for effective separation. - Filtration, distillation, and centrifugation are not appropriate for separating oil and water due to their specific limitations. - Understanding the properties of the substances involved is crucial for selecting the right separation technique.