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Liquids generally have lower density as compared to solids.But you must have observed that ice floats on water.Find out why.

Ice floats in water because solid water (ice) is less dense than liquid water. This is unusual behavior: Most solids are more dense than the corresponding liquid and sink when placed in the liquid. The anomalous density behavior has to do with the tendency of water molecules in condensed phases to form four highly directional hydrogen bonds with neighboring molecules. Water in both the solid and liquid state forms hydrogen bonds because of the polar nature of the HOH molecule. The electronegative ends (nearest the oxygen) are strongly attracted to the electropositive ends (nearest the hydrogens) of adjacent molecules. In the frozen state, the molecules are held together by the hydrogen bonds in a crystalline structure with considerable space between them. When ice melts, many but not all of the bonds are broken, the regularity of the arrangement is broken up, and the space between the molecules decreases (density increases) up to a temperature of + 4 degrees C (+39 degrees F). Beyond that, density decreases again. Hydrogen bonding is responsible for other anomalous properties of water, such as its relatively high boiling point


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