why does ice float on water

Ice is solid form of water. We know many gases like oxygen, carbon dioxide are dissolved in water . Volume of these gases is more as molecules in gas can expand like they would do in infinity . When solidification of the water starts these gases get trapped , also the crystal structure of ice becomes uneven with presence of voids in it ,ie. Empty spaces . Just like bubble wrap though it have it’s own weight imagine bobble wrap without gas in it and in shape of solid mass , I guess it would have some solid density now ! Now when ice gets formed due to above reasons there is density difference !
Density is mass present in specific volume , now as mass per unit volume of ice is reduced due to voids , the density decreased , and whatever is denser goes down hence ice floats on water !