Matter has a definite shape and volume when it is in the solid state.

Here's why:

* Solid: The particles in a solid are tightly packed together and vibrate in fixed positions. This strong attraction between particles gives solids their rigid structure.

* Shape: Because the particles are locked in place, solids maintain their shape regardless of the container they are in.

* Volume: Since the particles are tightly packed, the volume of a solid remains constant.

Let me know if you have any other questions!