Identifying the balanced chemical equation Steps:

• Check atom balance for each equation by counting elements on reactant and product sides.
• Option A: Left (Cu:1, O:2); right (Cu:1, O:3). Unbalanced.
• Option B: Left (Mg:1, S:1, O:2); right (Mg:1, S:1, O:3). Unbalanced.
• Option C: Left (Na:1, H:2, O:1); right (Na:1, H:3, O:1). Unbalanced.
• Option D: Left (Zn:1, H:2, N:2, O:6); right (Zn:1, H:2, N:2, O:6). Balanced. Why D is correct:
• Atoms of each element are equal on both sides, satisfying the law of conservation of mass in chemical equations. Why the others are wrong:
• A: Extra oxygen atom on product side.
• B: Extra oxygen atom on product side.
• C: Extra hydrogen atom on product side. Final answer: D