Answers are:
1) trough - lowest point of the wave.
2) crest - highest point of wave.
3) amplitude - distance from rest position to the crest or thoughs.
4) wavelenght - distance from two consecutive crest or troughs.
5) rest position - the flat line running through middle of the wave.
An accepted and universally true explanation of observed facts is a law.
The valence electrons should be the correct answer
Metal
Alkali metal
Period 4 element
