The lower density of ice compared to liquid water is due to the lower number of water molecules that form the crystal lattice structure of ice, which leaves a large amount of space between water molecules.
Addakud n aɣeris andarran d aman war n aqqiras issibab net addakud andarran n molecule tan n aman wi taqqal nen crystal lattice n aɣeris itay in addikud n edag maqqoran jir molecule tan n aman