Which of the following terms defines the average kinetic energy of particles in a substance?

The term that defines the average kinetic energy of particles in a substance is temperature. Temperature is a measure that reflects how fast the particles are moving; the higher the temperature, the faster the particles are moving, indicating a greater average kinetic energy. This concept is fundamental in thermodynamics and helps in understanding how heat is transferred between objects.

In contrast, conduction refers to the process of heat transfer through direct contact between materials, and heat is a form of energy transfer related to temperature differences. Pressure is the force exerted by particles when they collide with the walls of their container, which is related to temperature but does not directly quantify the average kinetic energy of those particles. Therefore, temperature is the most accurate term in this context.