Why are rest and motion called reletive terms

Rest and motion are the relative terms because they depend on the observer’s frame of reference. If an observer is at rest in his or her own frame of reference, but he may be moving in other observer's frame of reference.

Explanation:

answer: the correct answer id option(d).

explanation:

snell's law refraction:

the angle of refraction =

the angle of incidence =

refractive index of air = = 1

refractive index of glycerol = 1.47

from the given options, the most closest answer to 63.72° is 65° of option (d).