Is the linear momentum of an object conserved in the following cases?

Question

the force acting on the object is conservative?
there is a single, unbalanced internal force acting on the object?
the mechanical energy is conserved?
none of these?

Answer 1

I know for a fact that the conservative force acting on the object and mechanical energy is conserved (both essentially say the same thing) do not imply conservation of linear momentum. I am not entirely certain about the unbalanced internal force acting on the object, but would expect linear momentum to be conserved.