Find the refractive index of glycerine with respect to air if critical angle inside glycernine is `45^@`

Find the refractive index of a medium with respect to air if the critical angle inside the medium is 30^@

The refractive index of a denser medium with respect to a rare medum if critical angle is 60^@ for the two media, is

State whether the following statements are True (T) or False (F): The relative index of refraction of a medium with respect to air can be less than one.