According to the kinetic molecular theory, what happens to the gas molecules in a container when thermal energy is applied?

• A. The average speed of the gas molecules increases.
• B. The gas molecules decrease in size.
• C. The number of gas molecules in the container increases.
• D. The gas molecules lose energy and move more slowly.

Answer: (A)

Verified step by step guidance

1. Recall the kinetic molecular theory, which explains the behavior of gas molecules in terms of their motion and energy.
2. Understand that thermal energy added to a gas increases the kinetic energy of the gas molecules.
3. Recognize that kinetic energy is directly related to the speed of the gas molecules, so increasing thermal energy causes the molecules to move faster on average.
4. Note that the size of gas molecules does not change with temperature, and the number of molecules in a closed container remains constant.
5. Conclude that when thermal energy is applied, the average speed of the gas molecules increases, consistent with the kinetic molecular theory.