The odd question
Why does ice float when most solids sink?
Frozen water breaks the rule followed by many other substances.
Here's the surprise
Ordinary ice is less dense than liquid water, even though most substances become denser when they freeze.
What's really going on?
As water freezes, hydrogen bonds help arrange molecules into an open crystal structure.
That structure takes up more space than the same mass of liquid water, lowering the density of ice.
Floating ice insulates the water beneath it, helping lakes and aquatic life survive cold winters.
Think about it
What happens to the volume of a fixed mass of water when it freezes?
Reveal the explanation
It generally expands, which is why ice is less dense and floats.