Which factor determines the state of matter primarily?

• A. Pressure
• B. Temperature
• C. Volume
• D. Color

Answer: (B)

Temperature controls the kinetic energy of the particles, and that energy determines which phase the material adopts. When temperature is low, particles don’t have enough energy to break their intermolecular forces, so they stay arranged in a solid. As temperature rises, particles gain energy and can slide past one another, forming a liquid. Increase the temperature further and the energy becomes sufficient for particles to move freely as a gas. Pressure and volume can influence where the boundaries between these phases lie, but the primary driver for changing from solid to liquid to gas is temperature. Color has no effect on the state of matter.