Answer:
the answer is D. the molecules of a gas are small compared to the distance between them
Step-by-step explanation:
The postulates of Kinetic-Molecular Theory are as follows:
The molecules of a gas move rapidly, constantly, and in straight lines.
The average kinetic energy of the molecules of a gas is directly proportional to the Kelvin temperature.
A gas exerts pressure because the gas molecules repel each other.
The molecules of a gas are small compared to the distance between them1.
Therefore, “the molecules of a gas are small compared to the distance between them” is not a postulate of Kinetic-Molecular Theory