Final answer:
Only option A (2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O) is a balanced chemical equation, with the correct number of carbon, oxygen, and hydrogen atoms on both the reactant and product sides.
Step-by-step explanation:
The correct answer is A (2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O).
To determine whether a chemical equation is balanced, we need to ensure that the number of atoms on both sides of the equation is equal. In the given reactions, A and C are already balanced because the number of atoms is the same on both sides of the equation.
However, B is unbalanced because there are two iron (Fe) atoms on the left side and six iron (Fe) atoms on the right side of the equation. D is also unbalanced because there are two hydrogen (H) atoms on the left side and six hydrogen (H) atoms on the right side of the equation. To balance the equation, we need to multiply NaHCO₃ by 2 to get 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂.