I'll leave this here:
https://legacy.etap.org/demo/biology_files/lesson6/instruction4tutor.html
Answer:
When the Earth Rotates on its axis.
Explanation:
That is how the whole day/night cycle on earth progresses, is by the earth rotating on its axis. None of the others would work.
If the element has not become an ion yet, then there is 73 electrons.
Number of protons = number of electrons**
**only when the element has not form an anion or cation.