Question

as we stand and watch the hot air balloon rise in the sky, we can imagine what is happening at the microscopic level to the gas molecules inside the balloon. as the balloon rises, the gas molecules are
a moving faster and spreading apart.
b slowing down and moving closer together.
c gradually escaping from the confines of the balloon.
d all collecting at the top of the balloon, pushing upward.

Explanation:

As a hot - air balloon rises, the outside pressure decreases. The gas inside the balloon heats up, causing the gas molecules to gain kinetic energy, move faster, and spread apart, which makes the balloon expand and rise.

Answer:

A. moving faster and spreading apart