Final answer:
Using the stoichiometric relationship of the balanced chemical equation CH4 + 2O2 → CO2 + 2H2O, for every 10 moles of H2O produced, 5 moles of CO2 are produced, since the ratio of methane to water is 1:2 and methane to carbon dioxide is 1:1.
Step-by-step explanation:
If 10 moles of H2O are produced in the chemical reaction CH4+2O2→CO2+2H2O, we can use the stoichiometry of the balanced equation to determine how many moles of CO2 are also produced. The balanced equation shows a 1:1 ratio between methane (CH4) and carbon dioxide (CO2), and a 1:2 ratio between methane and water (H2O). Since 10 moles of water are produced, we can infer that 5 moles of methane were used because it takes 1 mole of methane to produce 2 moles of water.
Following the 1:1 ratio between methane and carbon dioxide in the chemical equation, if 5 moles of methane produce 10 moles of water, then these 5 moles of methane will also produce 5 moles of CO2. Therefore, the answer to the student's question is (a) 5 moles of CO2 are produced when 10 moles of H2O are formed.