The long tube in the ground that connects the magma chamber to earth’s surface is called the

Pipe is the long tube in the ground that connects the magma chamber to the Earth's surface.

The volcano's vent is the point of the Earth's surface where magma leaves the volcano's pipe.

Flow of magma:

Magma chamber ⇒⇒ Pipe (Conduit) ⇒⇒ Vent