Answer:
D It must be equal to 1.00
Explanation:
The refraction in the second medium must be equal to 1. The refraction index is given as the ration of the angle of incidence to the angle of refraction. This is given as a fraction. In other words:

where Θ₁ and Θ₂ are angles of incidence an refraction, and n is the refractive index.
At a critical angle, the refraction is equal to the reflection inside the medium. This results in a phenomenon called total internal reflection where light is reflected internally in the medium.
The answer is A ( pure water has no free ions)
Ce clasă ești sa văd daca te pot ajuta
Answer:
2 and 3 because there are the protons and neutrons which have a greater mass than the electrons which are found in the locations 1 and 4. The atom contains a nucleus, which is made from protons and neutrons, and electrons which are found around the nucleus. The mass of the atoms is concentrated in the very tiny space represented by the nucleus. Of course the electrons have a mass too, but is very small compared to the protons and neutrons, and we usually neglect its mass.