Final answer:
The final yield of H₂O when 0.240 mol of methane reacts with oxygen is 0.480 moles. This is based on the balanced chemical equation for the combustion of methane, which shows that one mole of methane yields two moles of water.
Step-by-step explanation:
To determine the final yield of H₂O in moles when 0.240 mol of methane (CH₄) reacts completely with oxygen, we need to look at the balanced chemical equation for the combustion of methane:
CH₄ + 2 O₂ → CO₂ + 2 H₂O
According to the stoichiometry of the reaction, one mole of methane produces two moles of water. Therefore, if we start with 0.240 moles of methane, the amount of water produced will be:
(0.240 moles CH₄) x (2 moles H₂O / 1 mole CH₄) = 0.480 moles H₂O
So, the correct answer to the question is B. 0.480 moles.