镁条在二氧化碳中燃烧的化学方程式

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2Mg+CO2=点燃==2MgO+C

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点燃
Mg+CO2 == C+MgO

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2Mg + CO2 === 2MgO + C
(第二个“2”是下标，等号上写上“点燃”)

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2Mg+CO2=2MgO+C(条件是“点燃”)

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