Introduction:
Liquids are generally less dense than solids due to the arrangement of their molecules. However, ice floats on water, which seems to contradict this principle. This phenomenon has important implications for the survival of aquatic life and the planet's climate.

Density of water vs. ice:
Water molecules are arranged in a relatively dense and compact manner. When water freezes and turns into ice, the molecules form a crystalline structure that is less dense than liquid water. As a result, ice floats on top of water.

Hydrogen bonding:
The reason behind ice floating on water is due to hydrogen bonding. Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom bonded to an electronegative atom (such as oxygen) is attracted to another electronegative atom in a neighboring molecule. In the case of water, hydrogen bonds form between the hydrogen atoms of one molecule and the oxygen atoms of another.

Arrangement of molecules:
In liquid water, the hydrogen bonds are constantly breaking and reforming as the molecules move around. This allows the water molecules to pack closely together, making it more dense than ice. In contrast, the hydrogen bonds in ice are more stable, which causes the molecules to form a crystal lattice structure that is less dense than liquid water.

Impact on the planet:
The fact that ice floats on water has important implications for the planet's climate. In colder regions, such as the polar ice caps, ice forms on the surface of the water and acts as an insulating layer, preventing further freezing of the water below. If ice were denser than water, it would sink to the bottom and continue to freeze, eventually leading to the entire body of water freezing solid. This would have devastating consequences for aquatic life and the planet's climate.

Conclusion:
In summary, ice floats on water because it is less dense than liquid water due to the stable hydrogen bonds that form a crystal lattice structure. This phenomenon has important implications for the survival of aquatic life and the planet's climate.

Liquids generally have lower density than solids but in case of water and ice is not that because ice have minutes pore in its structure which are filled with air .

for a given time the volume of ice is more than that of water but it's density is less than water.