Aluminum reacts with oxygen gas to produce aluminum oxide: Al + O₂ → Al₂O₃. When this equation is balanced using the smallest whole-number coefficients, what is the coefficient of O₂?
A1
B2
C3
D4
Explanation
📌 Balanced: 4 Al + 3 O₂ → 2 Al₂O₃. Start by balancing aluminum: 2 Al₂O₃ contains 4 Al, so you need 4 Al on the left. Then balance oxygen: 2 Al₂O₃ contains 6 O atoms; since O₂ provides 2 O per molecule, you need 3 O₂. Always balance metals/nonmetals first and leave free elements (like O₂) for last.
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