Answer:
4Al + 3O₂ → 2Al₂O₃
Explanation:
4Al + 3O₂ → 2Al₂O₃
Only this reaction above obeys the law of conservation of mass. The others flout the rule.
The law of conservation of mass states that "matter is neither created nor destroyed in a chemical reaction but are simply transformed from one form to another".
By this law, the number of atoms on both sides of expression must be the same;
Number of atoms
Elements Left hand side Right hand side
Al 4 4
O 6 6
