Balanced combustion equation determines oxygen moles

Steps:

• Write the formula for ethanol: C₂H₅OH.
• Form the combustion equation: C₂H₅OH + O₂ → CO₂ + H₂O.
• Balance it: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O (3 moles O₂ per mole ethanol).
• For 2 moles ethanol: 2 × 3 = 6 moles O₂.

Why C is correct:

• The stoichiometry of the balanced equation requires 3 moles O₂ per mole C₂H₅OH, so 6 moles for 2 moles.

Why the others are wrong:

• A: Ignores oxygen for hydrogen atoms in ethanol.
• B: Matches 1 mole ethanol, not 2.
• D: Overcounts by assuming extra oxygen for incomplete reaction.

Final answer: C