so the first one is sodium chloride
second one is Magnesium oxide
Third one is Calcium hydroxide
You just have to write them in their word form;
1 - 3 molecules of sodium chloride.
2 - 4 molecules of magnesium oxide.
3 - [tex](OH)^{2}[/tex] stands for "hydroxide" and can be added to many different molecules.
Hope it helped,
BioTeacher101
