Final answer:
An unknown substance, where particles vibrate in fixed positions, is in a solid state. The particles in a solid are closely packed together and only vibrate in place, different from particles in liquids, gases, and plasmas
Step-by-step explanation:
The state of matter of an unknown substance, which's particles vibrate in fixed positions, is a solid. In the solid state, particles are tightly packed together and cannot move freely; they only vibrate in place. This contrasts with other states of matter such as liquids, gases, and plasmas, where the particles have more freedom of movement. A defining characteristic of a solid is that it retains its shape without a container, unlike liquids and gases.
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