| 1 | This chemical reaction will generate a huge amount of carbon dioxide. | |
| 2 | Burning coal increases the amount of carbon dioxide in the atmosphere. | |
| 3 | How come a big ice age happened when carbon dioxide levels were high? | |
| 4 | Carbon dioxide produced by burning gasoline can be harmful to the environment. | |
| 5 | Combustion is a chemical reaction, and its main products include carbon dioxide, water, and nitrogen oxides. |