Did you know, Why does ice float on Water ?

We know ice is made of water, even then why does ice float on top of liquid water, instead of sinking to the bottom?

Before we talk about the reason of floating of ice on the water, first, let's take a look at why anything floats.
We knowthat a substance floats in a liquid if its density i.e. mass per unit volume is less than the density of the liquid. For example, if you put some pieces of stones or rocks into a bucket of water, they sink because they are denser than the compared to the water. Basically, the rocks push the water out of the way, or displace it. According to Archimedes Principle, for an object to be able to float, it has to displace a weight of fluid equal to its own weight.

When water is cooled down, it reaches its maximum density at 4°C (40°F). As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid (frozen) state than in their liquid state. Water is different because of hydrogen bonding. A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively charged hydrogen atoms and the negatively charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.

Ice is put in water surface; it floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water. It means that a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, that is why ice floats to the top of the water.
In fact the lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.