Final answer:
When the substance is allowed to approach T1, the average kinetic energy of the substance is decreasing. The correct answer is option A. The average kinetic energy is decreasing
Step-by-step explanation:
According to kinetic-molecular theory, the temperature of a substance is proportional to the average kinetic energy of its particles. Raising the temperature of a substance will result in more extensive vibrations of the particles in solids and more rapid translations of the particles in liquids and gases. At higher temperatures, the distribution of kinetic energies among the atoms or molecules of the substance is also broader (more dispersed) than at lower temperatures. Thus, the entropy of any substance increases with temperature.
When a substance is heated to temperature T2 and allowed to approach temperature T1, the average kinetic energy of the substance will decrease. This is because as the temperature decreases, the particles of the substance will have less energy and move with slower average velocities. Therefore, the correct answer is option 1: The average kinetic energy is decreasing.
Thus, the correct answer is option A. The average kinetic energy is decreasing