How does temperature relate to the motion of molecules in a substance?

The correct answer highlights the relationship between temperature and the kinetic energy of molecules. Temperature is a measure of the average kinetic energy of the particles in a substance. As temperature increases, the average energy of molecular motion also increases, which means that the molecules move more vigorously and collide more often and with greater force.

In contrast, at lower temperatures, the average kinetic energy decreases, leading to slower movements of the molecules. This is a fundamental concept in thermodynamics and explains why substances can change states (from solid to liquid to gas) as temperature changes. For example, heating a solid typically increases the molecular motion enough to eventually break the forces holding the molecules in place, allowing the solid to melt.

Understanding temperature in this context is crucial, as it not only influences molecular motion but also affects properties such as pressure, volume, and state of matter.