What happens at a continent-oceanic convergent boundary?
An oceanic plate goes under a continental plate and causes volcanism on the continental plate.
This occurs because the continental plate is less dense.
An example of oceanic slab subduction would be the Andes mountains of South America, which run along the western side of that continent.
Mountain ranges can form when two continental plates collide as, it is more difficult for one plate to subduct under the other.