The state of matter that keeps its shape and volume when placed in a different container is a solid.

Here's why:

* Solids have tightly packed particles that vibrate in fixed positions. This rigid structure gives them a definite shape and volume. They resist changes in both.

* Liquids take the shape of their container but maintain a constant volume.

* Gases take the shape and volume of their container.

Let me know if you have any other questions about states of matter!