Modern cars have devices that combine oxygen with carbon monoxide, a toxic gas produced by car engines. This reaction produces carbon dioxide, which is less toxic.
Consider the following reaction:
2 molecules of oxygen (O2) react with 4 molecules of carbon monoxide (CO) to produce some amount of carbon dioxide (CO2).
Complete the table below.
Chemical element Number of atoms in the reaction


During this reaction, how many molecules of carbon dioxide (CO2) are produced?