I am not going to give you the answer to this. However, I will give you some hints. The key to finding the answer is to determine the limiting factor in the chemical reaction. The easiest way that I can think of to do this would be to convert each of the weights to Mols. You can do this by looking up the molar weights on a periodic table such as this one (http://www.lenntech.com/periodic-chart.htm). (Your daughter should also have one in her textbook.) Once you have the mols of each, you need to remember that you need twice as many oxygen atoms as you do carbon atoms to make CO2. So, with the first case, do you have any carbon atoms left over? If not, then you can't make any more CO2 by increasing the amount of oxygen. If you do have left over carbon atoms, then more CO2 can be created by adding more oxygen to the reaction. So, you will have to figure how much would be created by adding the extra oxygen. Here is another hint for you that I noticed as I thought a bit more about this. Compare the total starting weight of oxygen and carbon to the weight of CO2 that they create. This will tell you if there is anything left over after the reaction is complete.