mass doesn't change
solid
it is a solid
the matter can change into liquid, solid and gas.
Heating can change matter from a solid to a liquid or from a liquid to a gas. Cooling can change matter from a gas to a liquid or from a liquid to a solid.
Solid state of matter is characterized by resistance to a change in volume or shape.
Physical change
When something changes between solid, liquid, gas, or plasma
state of matter
This change in the state of matter (liquid to solid) is called freezing; it is a physical change, the chemical nature of the molecules is not changed.
Ice is the solid state of matter for water. Being a solid is a physical property, not a change.
If you add heat to matter, it can either get it hotter, or it can change the state of matter (for example, from solid to liquid).
freezing