Question

choose the correct answer.
particles tend to speed up when what happens to them?
they are cooled.
they are heated.
particle motion always stays the same.

Explanation:

When particles are heated, the heat energy is transferred to them. This causes the particles to gain kinetic energy. Kinetic energy is related to the motion of particles. As the kinetic energy increases, the speed of the particles increases. On the other hand, when particles are cooled, they lose kinetic energy and slow down. And it is incorrect to say that particle motion always stays the same as external factors like heating or cooling can affect their motion.

Answer:

They are heated.