Question

For each molecule of propane (C3H8) that burns, three molecules of carbon dioxide are produced (3CO2). How many total oxygen atoms are in those molecules?

Answer 1

Given the criteria, there are six because there are three Carbon dioxide molecules and di means two; so two times three us six. But if u look at the whole reaction *pictured below* u will see that in the entire reaction there are 10 Oxygen reacting through the whole thing.
*the triangle is the Greek letter delta and it symbolizes heat in a reaction.