Which property best describes a solid?

• A. Definite shape and volume; cannot flow; low energy.
• B. No definite shape or volume; high energy.
• C. Definite volume; can flow.
• D. Extremely high temperatures; ionized state of matter.

Answer: (A)

The idea being tested is how the arrangement and energy of particles determine a state of matter. A solid is characterized by particles that are tightly packed and vibrate in place, keeping a fixed arrangement. This gives the substance a definite shape and a definite volume, and the structure doesn’t flow like a liquid or gas because the particles don’t slide past one another easily. The energy per particle in a solid is relatively low compared to liquids and gases, which helps maintain that rigid structure.

That’s why the description “definite shape and volume; cannot flow; low energy” best fits a solid. The other descriptions describe liquids (definite volume but can flow) and gases (no definite shape or volume; high energy), or describe a different state of matter altogether (plasma, which involves ionized particles at extremely high energy).