NEET 2018 Physics and Chemistry

The refractive index of the material of a prism is √2 and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path(after reflection from the silvered surface) if its angle of incidence on the prism is