Final answer:
Pumice is a type of rock that is expelled during volcanic eruptions, known for being lightweight and able to float on water. The true or false statement about rocks gaining kinetic energy as they rise and gaining potential energy as they fall is false; it's actually the reverse.
Step-by-step explanation:
The original question posits a scenario about rock behavior during a volcanic eruption, however, there seems to be some confusion in the statement. To clarify, when a volcano erupts, it often expels pumice, which is a type of vesicular felsic igneous extrusive rock. Pumice is known for its lightweight and frothy nature due to the many gas bubbles trapped within it at the time of solidification. Pumice rocks do tend to shoot up into the air during volcanic eruptions due to the explosive force and can remain afloat if they land on water because of their low density.
The answer to the True or False statement under discussion is that it is false. As a rock is thrown into the air, its potential energy increases with height due to gravitational potential, while its kinetic energy decreases as it slows down. Conversely, as the rock falls back to the ground, its kinetic energy increases due to acceleration by gravity, and its potential energy decreases.