Answer:
Because there are other elements that get in touch with it. And over time with, evolution, erosion and temperature their particles tend to mix. So what once was very common became mixed over time.
Based on how they each acted in the trials, the substance that would be the most metallic is B.
Answer:
a) The angle of refraction is approximately 34.7
b) The angle the light have to be incident to give an angle of refraction of 90° is approximately 53.42°
Explanation:
According to Snell's law, we have;

The refractive index of the glass, n₁ = 1.66
The angle of incident of the light as it moves into water, θ₁ = 27.2°
a) The refractive index of water, n₂ = 1.333
Let θ₂ represent the angle of refraction of the light in water
By plugging in the values of the variables in Snell's Law equation gives;


θ₂ = arcsin(0.5692292265) ≈ 34.7°
The angle of refraction of the light in water, θ₂ ≈ 34.7°
b) When the angle of refraction, θ₂ = 90°, we have;


θ₁ ≈ arcsin(0.803) ≈ 53.42°
The angle of incident, θ₁, that would give an angle of refraction of 90° is θ₁ ≈ 53.42°
The suns right ascension on the vernal equinox is (a) 0 hours