Question

Recall the postulates of kinetic-molecular theory. Read the list and check all the statements that apply to the behavior of an ideal gas:

gas particles behave like hard spheres

gas particles travel randomly

gas particles are attracted to each other

energy is lost when gas particles collide

average kinetic energy of a collection of gas particles depends on the temperature

gas particles occupy most of the space within a container

gas particles have mass and volume

Answer 1

Correct for an ideal gas (kinetic‑molecular theory):

- gas particles travel randomly — True. Particles move in straight lines between collisions in random directions.
- average kinetic energy of a collection of gas particles depends on the temperature — True. KE ∝ T (absolute temperature).

Not correct for an ideal gas:

- gas particles behave like hard spheres — Not really. The model treats particles as pointlike with negligible volume; collisions are treated as instantaneous/elastic (sometimes idealized like hard-sphere collisions), but the particle volume is assumed negligible.
- gas particles are attracted to each other — False. Ideal gas postulate: no intermolecular forces except during collisions.
- energy is lost when gas particles collide — False. Collisions are elastic, so kinetic energy is conserved.
- gas particles occupy most of the space within a container — False. The particles occupy negligible volume compared with the container.
- gas particles have mass and volume — Partly true in reality they have both, but in the ideal-gas model their volume is neglected. So as stated (have volume) — not true for an ideal gas.