In the kinetic theory of gases, the pressure exerted by an ideal gas on the walls of its container is proportional to which of the following combinations of molecular quantities?
Show the answer and explanation
Correct answer
A. Number density and average translational kinetic energy
Principle or equation
For an ideal gas, the pressure is given by p = (1/3) n m , where n is the number density, m is the molecular mass, and is the mean square speed. Since the average translational kinetic energy is = (1/2) m , the pressure is proportional to n .
Why this answer is correct
The kinetic theory derivation shows p = (1/3) n m = (2/3) n . Thus pressure is directly proportional to the number density n and the average translational kinetic energy .
Example
If the number density is doubled while the average kinetic energy remains constant, the pressure doubles. If the average kinetic energy is tripled at constant number density, the pressure triples.
This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.