Law of refraction?

Question

Suppose you have an unknown clear substance immersed in water, and you wish to identify it by finding its index of refraction. You arrange to have a beam of light enter it at an angle of 45 degrees, and you observe the angle of refraction to be 40.3 degrees. What is the index of refraction of the substance and its likely idenfification?

Answer 1

n =sin45/sin40.3