Answer the following question:
Find out, from Table, the medium having highest refractive index. Also find the medium with lowest refractive index.
Absolute refractive index of some material media
The optical density of a medium is related to its refractive index.
A medium with the lowest refractive index will have the optical density and vice-versa.
So,
Lowest refractive index -
Highest refractive index -