Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
Usually solids have higher densities than liquids, and hence the solids sink in liquids.
But ice, even though a solid, floats in water (a liquid)
This is because when water freezes into ice, it has space in it which contains air.
Whereas water does not have any such space in it.
Due to the spaces containing air, the density of ice is less than the density of water.
Hence, ice floats on water.