Question

7.The _____ theory of matter states that all particles of matter are in constant motion.

Answer 1

The kinetic energy theory of matter states that all particles of matter are in constant motion.
Kinetics has to do with some kind of movement, which is why this answer is the only plausible one. 

Answer 2

The kinetic theory of matter states that all particles of matter are in constant motion.

The following are the postulates of kinetic theory of gases:

1. The particles of gases are in constant and random motion. Due to this motion, they collide with each other and walls of the container.

2. The particles of gases have point mass and zero volume.

3. The particles of gases have no such attraction or repulsion between them.

4. The kinetic energy with which the particles are moving is directly proportional to temperature. A temperature increases, kinetic energy also increases, and particles collide each other more frequently.

5. The particle of gases at given temperature have same kinetic energy.