Combustion stoichiometry determines mole ratio from product volumes

Steps:

• Balanced equations: C₂H₅OH → 2CO₂ + 3H₂O; CH₃OH → 1CO₂ + 2H₂O.
• Volumes proportional to moles: 2E + M = 35 (CO₂); 3E + 2M = 55 (H₂O), where E and M are relative moles.
• Multiply first equation by 2: 4E + 2M = 70; subtract second: E = 15.
• Substitute: M = 5; ratio E:M = 3:1.

Why D is correct:

• Solving the system yields E:M = 3:1, matching the ethanol:methanol ratio.

Why the others are wrong:

• A. 1:3 gives CO₂:H₂O = 5:9, not 35:55.
• B. 2:3 gives CO₂:H₂O = 8:12 (2:3), not 7:11.
• C. 3:2 gives CO₂:H₂O = 9:13, not 7:11.

Final answer: D