Question

find out the medium have highest optical density also find the medium with lowest density ​

Answer 1

here answer of your question ...

the median with the highest refractive index will have the highest optical density ,Diamond has the highest refractive index so it has the highest optic density.

similarly the medium with the lowest refractive index will have the lowest optcal density

so air is the lowest optical density.

hope this will help you

Answer 2

highest = diamond

lowest = air