Balancing the combustion equation for hexan-3-ol

Steps:

• Write the formula for hexan-3-ol as C₆H₁₄O.
• For complete combustion: C₆H₁₄O + xO₂ → 6CO₂ + 7H₂O.
• Balance oxygen atoms: products need 12 (from CO₂) + 7 (from H₂O) = 19; fuel provides 1, so 18 from O₂.
• Thus, x = 9 molecules of O₂.

Why A is correct:

• The balanced equation requires exactly 9 O₂ molecules to account for all oxygen atoms in products after the fuel's contribution.

Why the others are wrong:

• B ignores the oxygen atom in the alcohol, undercounting by 1.
• C counts O atoms instead of O₂ molecules.
• D double-counts the alcohol's oxygen or miscounts hydrogens.

Final answer: A