Proper balancing of the combustion equation for butanol Steps:

• Identify atoms in C4H9OH: 4 C, 10 H (from C4H9OH), 1 O.
• Balance carbon atoms: requires 4 CO2 on product side.
• Balance hydrogen atoms: requires 5 H2O on product side (10 H total).
• Balance oxygen atoms: products need 13 O (8 from CO2 + 5 from H2O); 1 O from butanol leaves 12 O needed from O2, so 6 O2.

Why A and D are correct:

• They use 6 O2, conserving atoms per the law of conservation of mass in balanced equations.

Why the others are wrong:

• B: Uses 6½ O2, providing 13 O atoms from oxygen (plus 1 from fuel = 14 total), mismatching 13 O in products.
• C: Uses 6½ O2, providing 13 O atoms from oxygen (plus 1 from fuel = 14 total), mismatching 13 O in products.

Final answer: A and D