Propane burns in oxygen: C₃H₈ + __O₂ → 3CO₂ + 4H₂O. What number goes in front of O₂?
Answer and explanation
Correct answer: A. 5
- Step 1: Count oxygen atoms on the right: 3 × 2 + 4 × 1 = 10.
- Step 2: Each O₂ has 2 atoms, so 10 ÷ 2 = 5.
Answer
5.
Why not the others: 3: the oxygen in the water was ignored. 7: the oxygen atoms were over-counted. 10: the oxygen atoms were double counted.
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