Which of the following mixtures can be separated by filtration?

• A. Salt and water
• B. Sand and water
• C. Sugar dissolved in ethanol
• D. Air and water vapor

Answer: (B)

Verified step by step guidance

1. Understand the principle of filtration: Filtration is a technique used to separate a solid from a liquid when the solid is insoluble and forms a heterogeneous mixture (a suspension). The solid particles are trapped by the filter, while the liquid passes through.
2. Analyze each mixture to determine if it is a suspension or a solution: - Salt and water: Salt dissolves in water forming a homogeneous solution, so filtration cannot separate them. - Sand and water: Sand does not dissolve in water, forming a heterogeneous mixture (suspension), so filtration can separate them. - Sugar dissolved in ethanol: Sugar dissolves in ethanol forming a solution, so filtration cannot separate them. - Air and water vapor: Both are gases and form a homogeneous mixture, so filtration is not applicable.
3. Identify the mixture that forms a suspension with solid particles large enough to be trapped by a filter, which is sand and water.
4. Conclude that filtration is effective only for mixtures where the solid is insoluble and suspended in a liquid, such as sand and water.
5. Remember that filtration cannot separate dissolved substances or gases; other separation methods like evaporation or distillation are needed for those.