A Face
Solid.
Mercury does have a solid surface
FacesE.g. Faces of a cube
mercury does have a solid surface
It does not have a flat surface.
The flat surface that goes on and on in all directions has no boundaries. This flat surface is called infinite surface. Accordingly, the answer is that the flat surface that goes on and on in all directions is called an infinite surface.
A flat, level surface is a plane.
A plane is a flat surface with no thickness
A mirror with a flat surface - planar
It is a drawing of the earth on a flat surface
Its base is a flat surface
A flat surface generally refers to a horizontal surface and is referred to as the plane.