National League for Nursing (NLN PAX) Practice Exam

The correct response is that the average kinetic energy of a substance increases when its temperature increases. This is rooted in the fundamental principles of thermodynamics and kinetic molecular theory, which state that temperature is directly proportional to the average kinetic energy of the particles in a substance.

As temperature rises, particles gain energy and move more rapidly. This increased motion results in higher average kinetic energy, as each particle vibrates, rotates, and translates with greater speed. Essentially, the kinetic energy of molecules is a reflection of their thermal energy; therefore, as the temperature increases, so does their kinetic energy.

In contrast, when temperature decreases, the average kinetic energy diminishes because the motion of the particles slows down. Transitions from liquid to solid involve a loss of kinetic energy as particles become more closely packed and move less, while the transition from liquid to gas typically requires energy input, leading to an increase in kinetic energy due to greater freedom of motion among particles.