Which of the following best explains why ice floats on water?

• A. Ice is less massive than water for the same volume.
• B. Ice has a lower density than liquid water due to its molecular structure.
• C. Ice is hydrophobic and repelled by water molecules.
• D. Ice contains trapped air bubbles that make it less dense than water.

Answer: (B)

Verified step by step guidance

1. Understand the concept of density, which is defined as mass per unit volume, given by the formula \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Recognize that whether a substance floats or sinks in a liquid depends on its density relative to the liquid; an object floats if its density is less than that of the liquid.
3. Recall that water expands when it freezes due to the formation of a crystalline structure held together by hydrogen bonds, which spaces the molecules further apart compared to liquid water.
4. This expanded structure means ice has a greater volume but roughly the same mass as the equivalent amount of liquid water, resulting in a lower density for ice.
5. Conclude that because ice has a lower density than liquid water, it floats, and this is primarily due to its unique molecular arrangement in the solid phase.