Select the incorrect statement about an ideal gas.

• A
  Molecules of a gas are in incessant random motion, colliding against one another and with the walls of the container.
• B
  The gas is not isotropic, and the constant $(1/3)$ in the equation $P = (1/3)\rho v^2_{rms}$ is a result of this property.
• C
  The time during which a collision lasts is negligible compared to the time of free path between collisions.
• D
  There is no force of interaction between molecules among themselves or between molecules and the wall, except during collision.