2NaOH + CaBr_{2} -> Ca(OH)_{2} + NaBr NO + Cl_{2} -> NOCl CaCO_{3} -> CaO + 2CO_{2} 2AlCl_{3} + 3Mg -> 3MgCl_{2} + 2Al
I gave my students this multiple choice question: Which equation is a balanced chemical equation?

Only one answer is correct among these 4 choices:
- 2NaOH + CaBr_{2} -> Ca(OH)_{2} + NaBr
- NO + Cl_{2} -> NOCl
- CaCO_{3} -> CaO + 2CO_{2}
- 2AlCl_{3} + 3Mg -> 3MgCl_{2} + 2Al

Could you tell me which one is correct?

2AlCl_{3} + 3Mg -> 3MgCl_{2} + 2Al