Final answer:
Volcanic mountains are formed by molten rock that erupts from beneath Earth's surface.
Step-by-step explanation:
The term that describes mountains formed by molten rock that erupts from beneath Earth's surface is Volcanic mountains. Volcanic mountains are formed when magma, or molten rock, rises to the surface and erupts through a vent or fissure. The magma solidifies and accumulates over time, creating a mountain.