Question

Explain why a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path

Answer 1

That's becoz at the pole the surface almost is plane and hence act as a plane mirror

Answer 2

A ray of light passing through the centre of curvature of a concave mirror retraces its path (gets reflected along the same path), because as the ray of light passes through centre of curvature of a concave mirror it strikes the mirror along the normal i.e. it incidences on to the mirror at 90 degree.