What factors does the refractive index of a medium depend on?

The refractive index of a medium depend on:

Optical density or we can say. nature of a medium .

Smaller the speed of light in a medium relative to air, higher is the refractive index of that medium.

Increase in temperature refractive index of the medium increases.

The refractive index of a medium depend on:

Optical density or we can say. nature of a medium .

Smaller the speed of light in a medium relative to air, higher is the refractive index of that medium.

Increase in temperature refractive index of the medium increases