The answer to this question is a
The number of waves passing in a certain amount of time
1. CaS
2. Nitrogen forms an anion with a -3 charge.
3. S
4. Ca2N3
5. Mg3N2. Magnesium nitride
6. CaO. So 1,1
7. 2- O2- (2- is super scripted). It is also an anion, which is a negatively charged ion.
8. That would be aluminum iodide AlI3, also called aluminum triiodide.
9. LiCI
These should be correct. Hope I helped. ^~^