Which method would be most effective for separating a mixture of sand and salt dissolved in water?

• A. Chromatography
• B. Distillation only
• C. Centrifugation
• D. Filtration followed by evaporation

Answer: (D)

Verified step by step guidance

1. Recognize the components of the mixture: sand (a solid, insoluble in water) and salt (which is dissolved in water, forming a solution).
2. Understand that filtration is used to separate an insoluble solid from a liquid or solution. Since sand does not dissolve, filtration will separate sand from the saltwater solution.
3. After filtration, the salt remains dissolved in the water. To recover the salt, evaporation is used to remove the water by heating, leaving the salt behind as a solid.
4. Chromatography is not suitable here because it is typically used to separate components of a solution based on their different affinities to a stationary phase, not to separate solids from solutions.
5. Distillation is more complex and unnecessary since the goal is simply to separate sand and salt; centrifugation is ineffective because sand is insoluble and will not separate by spinning in this context.