Describe the arrangement, movement and energy of particles in a liquid.

• A. Random arrangement, random movement, medium energy.
• B. Regular arrangement, no movement, low energy.
• C. Random arrangement, no movement, high energy.
• D. Regular arrangement, random movement, high energy.

Answer: (A)

In a liquid the particles are not held in a fixed, orderly pattern; they’re arranged randomly, squeezing close together but without a regular lattice like in a solid. Because the particles aren’t locked in place, they can slide past one another and flow, so their movement is random and not restricted to a fixed position. The energy of the particles is intermediate: enough kinetic energy to move and to overcome some local attractions, but not so high that they’re free to spread apart as in a gas. This combination—random arrangement, the ability to move and flow, and medium energy—explains why liquids have a definite shape that adapts to their container yet can flow and be poured.