| A | B |
|---|
 | ammonia (model of 1-molecule) |
 | carbon dioxide (model of 1-molecule) |
 | iron III oxide (model of 1-molecule) |
O-Fe-O,  | iron II oxide (model of 1-molecule) |
 | sodium chloride crystal |
 | sodium chloride (model of 1-molecule) |
 | water (model of 1-molecule) |
 | Gases in Dry Air |
| NH3 | formula for ammonia |
| CO2 | formula for carbon dioxide |
| H2O | formula for water |
| Fe2O3 | formula for iron III oxide |
| FeO | iron II oxide |
| NaCl | formula for sodium chloride |
| NaCl | formula for table salt |
