What is true about collisions between gas particles in the kinetic theory?

• A. Collisions between gas particles are inelastic, leading to a loss of kinetic energy.
• B. Collisions are elastic, meaning kinetic energy is conserved.
• C. Gas particles do not collide.
• D. Collisions cause permanent deformation of particles.

Answer: (B)

In the kinetic theory of gases, particles move quickly and mostly interact only during brief collisions. These collisions are treated as elastic, so the total kinetic energy of the colliding particles is the same before and after the collision, even though energy can be shuffled between particles. This means momentum is conserved and there’s no net loss of translational kinetic energy during a collision. That’s why the average kinetic energy of particles is linked to temperature, through the idea that temperature reflects the average translational kinetic energy in the system.

The idea that collisions are inelastic would imply some kinetic energy is lost as heat, sound, or deformation, which isn’t assumed in the basic kinetic theory. Saying there are no collisions is incorrect, since collisions are exactly how momentum and energy are redistributed. And permanent deformation would also indicate energy loss and dissipation, not what the model describes for idealized gas particles.