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

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

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

Correct the following sentences, if required changing the underlined portion. The refractive index of a medium depends on the angle of the minimum deviation.