The average kinetic energy of gas molecules is directly proportional to which temperature scale?

The average kinetic energy of gas molecules is directly related to the absolute temperature of the gas, which is measured using the Kelvin scale. In this scale, 0 Kelvin (absolute zero) represents a theoretical point where molecules have minimal kinetic energy and are at their lowest energy state. As the temperature increases in Kelvin, the kinetic energy of the gas molecules increases proportionally.

In contrast, the Celsius and Fahrenheit scales are relative temperature scales that do not begin at absolute zero; therefore, they cannot be used to directly relate average kinetic energy to temperature. For instance, at temperatures above absolute zero, both Celsius and Fahrenheit provide different numerical values that do not consistently reflect the kinetic energy of gas molecules. The Rankine scale, while also an absolute scale like Kelvin, is less commonly used in scientific contexts related to the behavior of gases.

Therefore, the direct proportionality of average kinetic energy to temperature exists only in the Kelvin scale, making it the most appropriate choice for this question.