GKFix MCQ Question

Which of the following equations is unbalanced?

• A. 4Fe(s) + 3O2(g) → 2Fe2O3(s)
• B. 2Mg(s) + O2(g) → 2MgO(s)
• C. P4(s) + 5O2(g) → P4O10(s)
• D. P4(s) + O2(g) → P4O10(s)