Question

Is optical density of a medium same as its mass density ? Name a transparent medium which has smaller mass density, but is optically denser.

Answer 1

No, Infact, mass density is mass per unit volume. Optical density of a medium determines the ability of the medium to refract light. Kerosene oil has higher refractive index than water. Therefore, kerosene oil is optically denser than water. But mass density of kerosene oil is less than the mass density of water.