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.
Answer:
Electron shell.Each shell can contain only a fixed number of electrons, the first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons.
(Hope it helped you!)
Explanation: