Crafting, reusing
Good luck!
Answer:

Explanation:
Using the given equation, we calculate the energy associated with the excited state
and 

Helium has an atomic number (Z) equal to 2, for n=8:

For n=4:

When an electron jumps from an energy level with greater energy
to one with lower energy
the wavelength of the emitted photon is given by:

h is the Planck constant and c the speed of light in vaccum. So, we have:

Answer:
v = 771.75 mile / h
Explanation:
The speed of sound is v = 343 m / s at T= 20C
the transformation ratios are
1 mile = 1600 m
1 h = 3600 s
Let's reduce
v = 343 m / s (1 mile / 1600 m) (3600 s / 1 h)
v = 771.75 mile / h
Plate tectonics may affect organic evolution because movement of plates may cause a change in the environment