Which of the following statements best describes the particles in a solid at room temperature? They are

Analyze the question: It asks about the arrangement and motion of particles in a solid at room temperature. This comes from the kinetic theory of matter.

Concept: In a solid, the particles are held in fixed positions by strong intermolecular forces. They are packed closely together in a regular pattern. They cannot move from place to place, but they have kinetic energy, so each particle vibrates about its fixed position. Particles are never completely stationary except at absolute zero (0 K).

Solution, option by option:

• A. Far apart and moving randomly: This describes a gas, so it is wrong.
• B. Close together and vibrating: Solid particles are tightly packed and vibrate about fixed positions, so this is correct.
• C. Close together and stationary: Particles at room temperature (about 25 °C, far above absolute zero) always have kinetic energy, so they are never stationary. This is wrong.
• D. Close together and moving randomly: This describes a liquid, where particles slide past each other. It is wrong.

**Answer: B.

Exam tip: Remember the three states of matter like this:

• Solid: close together and vibrating in place
• Liquid: close together and sliding past each other
• Gas: far apart and moving rapidly and randomly

Whenever you see "stationary" in a question about particles, be suspicious. Particles only stop moving at absolute zero.