Combustion volume ratios for hydrocarbons

Steps:

• Write balanced combustion equations for each option, assuming complete reaction to CO2 and H2O.
• Calculate oxygen volumes needed per volume of hydrocarbon, using Avogadro's law for gas volumes.
• Compare ratios to find the 1:5 match.
• Confirm products are only CO2 and H2O for all.

Why D is correct:

• Propane (C3H8) combusts as C3H8 + 5O2 → 3CO2 + 4H2O, requiring exactly 5 volumes of O2 per volume of propane.

Why the others are wrong:

• A. Butane (C4H10) requires 6.5 volumes of O2 (C4H10 + 6.5O2 → 4CO2 + 5H2O).
• B. Ethane (C2H6) requires 3.5 volumes of O2 (C2H6 + 3.5O2 → 2CO2 + 3H2O).
• C. Methane (CH4) requires 2 volumes of O2 (CH4 + 2O2 → CO2 + 2H2O).

Final answer: D