Admission Test for Dental Hygiene (ATDH) Practice

According to Kinetic Molecular Theory, which statement about particle behavior is true?

1. Particles have fixed positions.

2. Particles only collide with each other.

3. Particles are constantly in motion and collide with each other and walls of their container.

4. Particles move slowly and uniformly.

The correct answer is: Particles are constantly in motion and collide with each other and walls of their container.

The statement that particles are constantly in motion and collide with each other and the walls of their container is a fundamental principle of Kinetic Molecular Theory. This theory posits that all matter is composed of tiny particles that are in perpetual motion, whether in a solid, liquid, or gas state. This motion is what primarily affects temperature and pressure within a substance. When particles are in a gas state, for example, they move freely and rapidly, colliding with one another and with the walls of their container. These collisions are elastic, meaning that no energy is lost. The idea of constant motion and collision explains many physical properties of gases, such as their ability to expand to fill a container and their low density. In contrast, the other statements do not accurately represent the principles outlined in Kinetic Molecular Theory. Particles having fixed positions applies only to solids, where atoms or molecules are closely packed in a structured arrangement and can only vibrate in place rather than move freely. The notion that particles only collide with each other is misleading, as it overlooks the significant interactions with container walls. Lastly, stating that particles move slowly and uniformly does not capture the high-energy, random motion characteristic of particles in gases and some liquids. Therefore, the correct perspective on particle