Question

when the kinetic energy of particles in a substance decreases, what also decreases?
the size of the particles in the substance.
the number of particles in the substance.
the substances specific heat.
the substances temperature.

Explanation:

Step1: Recall kinetic - energy and temperature relation

Kinetic energy of particles is related to temperature.

Step2: Analyze the impact of kinetic - energy decrease

When kinetic energy of particles in a substance decreases, the average motion of particles slows down. Temperature is a measure of the average kinetic energy of particles in a substance. So, the substance's temperature decreases.

Step3: Rule out other options

The size of particles, number of particles, and specific heat are not directly related to a decrease in kinetic energy in this context.

Answer:

The substance's temperature.