. It has inversion symmetry just as V (r ⃗) has in 3 dimensions. The singularity at the origin (x = 0), although reminiscent of the singularity at r = 0 in the 3-D hydrogen atom, is more problematic as it separates the available coordinate space into two regions ( x > 0 and x < 0 ). The 'enigma' of the hydrogen atom in one dimension originates from this singularity at x = 0. (iv) What kind of spectrum (vis-à-vis the 3-D hydrogen spectrum) can be anticipated?