List the three ways volcanic moutains can form

Volcanoes can form at subduction zones where two plates collide, one being driven down into the mantle and the other riding over the top. This causes the lithospheric plate to melt and being less dense than the rock in the mantle it will rise. This rising magma will produce a volcano.
Volcanoes can form at a mid-ocean ridge. When the two plates separate magma fills the void and a volcano is produced. These chains of volcanic mountains are the longest mountain chain in the world.
Volcanoes can also form at a hot spot.