What property of water allows ice to float on it?

The property of water that allows ice to float on it is density. Water is unique in that its solid form, ice, is less dense than its liquid form. When water freezes, the molecules arrange themselves in a crystalline structure that takes up more space, thus making ice less dense than liquid water. This reduced density is why ice can float when placed in water.

In most substances, the solid form is denser than the liquid form, causing solids to sink. However, the opposite is true for water; this characteristic is crucial for aquatic ecosystems, as it helps insulate the water below and allows aquatic life to survive during colder periods. Understanding this density difference is essential in explaining various natural phenomena related to water bodies.