Here's why:

* Solid phase: Molecules are tightly packed and arranged in a regular, repeating pattern. They vibrate in place but don't move freely.

* Liquid phase: Molecules are closer together than in a gas but have more freedom of movement.

* Gaseous phase: Molecules are far apart and move freely.

Ice, being a frozen form of water, has molecules that are tightly bound together in a crystalline structure, exhibiting the characteristics of a solid.