All of us know that if we place a piece of solid iron in water, it will sink. It is because of the fact; the iron when placed in water displaces certain amount of water. The density of displaced water is less than that of the iron. So it sinks. This is a common rule applicable to all solids. But only exception is the ice.
Ice floats on Water! But how?
A solid floats in water when the density of the displaced water is greater than that of the solid itself. Ice floats in water in similar manner. This happens because of a chemical bonding called hydrogen bonding. Density of solid becomes less when it expands. Water freezes at zero degree centigrade to form ice and it expands. The density of ice decreases by 9% than the liquid water. As a result, ice is found to be floating in water.