Find the angle between the emergent ray and incident ray when the light goes from air to glass slab. Given ${\mu }_{glass}$ ​= 1.5

The correct option is C

$0^{\circ }$

If $i$ is the angle of incidence and $x$ is the refracted angle then at the second surface also $x$ will be the angle of incidence by alternate angle property.
By principle of reversibility of light, light will follow exactly the same path if its direction of travel is reversed. Using it on the second surface, angle $i$ will be the emergent angle which is equal to the incidence angle. So these two rays will be parallel. Hence, angle between incident ray and emergent ray = $0^{\circ }$