If same mass of liquid water and a piece of ice is taken, then why is the density of ice less than that of liquied water ?

Explanation

The structure of ice is of porous nature due to the presence of inter molecular hydrogen bonding in the `H_(2)O` molecules. When ice changes into liquid water, the extent of hydrogen bonding decreasing because that is supplied. As a result, the structure of water becomes less porous and its density is more that of the ice. For more details consult section 9:7