What happens to a light ray if it is incident on a reflective surface along the normal?

The incident ray and the reflected ray and the normal will be parallel to each other.

Explanation:

The normal is perpendicular to the surface of the mirror or the reflective surface.

According to the law of reflection which state that:

The angle of incidence is always equal to the angle of reflection on a smooth surface.

If a light ray is incident on a reflective surface along the normal. The angle of incidence will be at 90 degrees which will be perpendicular to the surface of the mirror, the reflected ray will bounce back likewise at the same angle which will be perpendicular to the reflective surface.

Both the incident ray and the reflected ray and the normal will be parallel to each other.