As water freezes to ice does its volume decrease or increase? Does the mass decrease or increase?

Hint: Water can exist in three different phases like solid, liquid, and gas. When water freezes to ice, the close packing of atoms leads to arrangement of a six-sided crystalline system. The crystalline system has less density which leads to the increase in volume.

Complete answer:
Water is a chemical compound with a molecular formula of $ {H_2}O $ , consisting of one oxygen and two hydrogen atoms. Water can exist in three different phases of matter i.e.. solid, liquid, and gas.
In the solid phase, water can be known as ice. In the liquid phase, water can be known as water only. In the vapor phase, water can be known as water vapor.
When the temperature decreases, water in the liquid phase freezes to ice. When water in a liquid state is considered, the atoms are arranged in a loose manner. When it freezes to ice, the atoms will be arranged in a closed crystal which is known as a six-sided crystalline system. This crystalline system has less density compared to water in liquid state.
Thus, water expands on freezing leads to the increase in volume. Whereas the mass will be constant either in liquid state or solid state.

Note:
Density is defined as the ratio of mass and volume; the mass is constant and volume increases when water undergoes a phase transformation from liquid to solid. As a result, the increase in volume leads to decrease in density. Thus, ice floats on water due to less density.