When oil, which is less dense than water, is mixed with water, what will happen?

• A. The oil and water will mix evenly to form a homogeneous solution.
• B. The oil will float on top of the water.
• C. The oil will dissolve completely in the water.
• D. The oil will sink to the bottom of the water.

Answer: (B)

Verified step by step guidance

1. Understand the concept of density: Density is defined as mass per unit volume, given by the formula \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Recognize that when two liquids are mixed, the one with lower density will float on top of the one with higher density because it is lighter per unit volume.
3. Recall that oil is less dense than water, meaning oil has a lower mass per unit volume compared to water.
4. Since oil is less dense, it will not mix evenly with water (which would form a homogeneous solution) nor dissolve completely, because oil and water are immiscible due to their different polarities.
5. Therefore, the oil will float on top of the water, forming a separate layer above the water.