Answer:
The light bends away from the normal
Explanation:
We can solve the problem by using Snell's law:

where:
is the index of refraction of the first medium
is the index of refraction of the second medium
is the angle of incidence (angle between the incoming ray and the normal to the interface)
is the angle of refraction (angle between the outcoming ray and the normal to the interface)
We can rearrange the equation as

In this problem, light travels from an optically denser medium to an optically rarer medium, so

Therefore, the term
is greater than 1, so

which means that the angle of refraction is greater than the angle of incidence, and so the light will bend away from the normal.
Answer:
the decay of half of the nuclei only a half-life has passed
, b) in rock time it is 1 108 years
Explanation:
The radioactive decay is given by
N = N₀
If half of the atoms have decayed
½ N₀ = N₀
½ =
₀
Ln 0.5 = - λ t
t = - ln 0.5 /λ
The definition of average life time is
= ln 2 / λ
λ = ln 2 / 
λ = 0.693 / 100 10⁶
λ = 0.693 10⁻⁸ years
We replace
t = -ln 0.5 / 0.693 10⁻⁸
t = 10⁸ years
We see that for the decay of half of the nuclei only a half-life has passed
b) in rock time it is 1 108 years