Balancing the combustion equation for butanol Steps:

• Balance carbon atoms: 4 C in C₄H₉OH requires y = 4 CO₂.
• Balance hydrogen atoms: 10 H in C₄H₉OH requires 2z = 10, so z = 5 H₂O.
• Balance oxygen atoms: right side has 2(4) + 5 = 13 O; left side has 1 (from OH) + 2x = 13, so 2x = 12 and x = 6 O₂.

Why D is correct:

• D (6, 4, 5) satisfies the law of conservation of mass by equating atoms on both sides in the balanced equation C₄H₉OH + 6O₂ → 4CO₂ + 5H₂O.

Why the others are wrong:

• A: x=5 provides only 11 O atoms (short 2), y=6 exceeds 4 C atoms.
• B: No values provided, so incomplete.
• C: x=5 provides only 11 O atoms (short 2), y=6 exceeds 4 C atoms.

Final answer: D