Why does ice float on water?
Show answer & explanation
Answer: Ice is less dense than water
Ice is filled with air bubbles — Wrong. While ice can trap some air bubbles, this isn't why it floats. Pure ice without bubbles still floats because its molecular structure makes it less dense than water.
Ice is less dense than water ✓ — Correct! Ice is less dense than liquid water, which is unusual. When water freezes, molecules arrange in a crystal structure with more space between them. This makes ice about 9% less dense than water. So ice floats! This property is important for aquatic life, as frozen lakes stay liquid underneath.
Water freezes from the bottom up — Wrong. Water actually freezes from the top down, not bottom up! Ice floats because its crystal structure is less dense than liquid water. This top-down freezing protects aquatic life beneath the ice layer.