Which of the following is an example of a solution?

• A. Oil and water
• B. Ice cubes floating in water
• C. Sand mixed with iron filings
• D. Salt water (NaCl dissolved in H2O)

Answer: (D)

Verified step by step guidance

1. Understand the definition of a solution: A solution is a homogeneous mixture where one substance (the solute) is uniformly dissolved in another (the solvent).
2. Analyze each option to determine if it forms a homogeneous mixture: For example, oil and water do not mix uniformly, so they form a heterogeneous mixture, not a solution.
3. Consider ice cubes floating in water: This is a physical mixture of two phases (solid and liquid), so it is not a homogeneous solution.
4. Look at sand mixed with iron filings: This is a mixture of solid particles that remain separate and can be physically separated, so it is not a solution.
5. Recognize that salt water (NaCl dissolved in H2O) is a classic example of a solution because the salt dissolves uniformly in water, forming a homogeneous mixture at the molecular level.