Which of the following is an equation representing a redox reaction?

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Multiple Choice

Which of the following is an equation representing a redox reaction?

Redox reactions involve the transfer of electrons, shown by changes in oxidation numbers. In this equation, magnesium starts in the zero oxidation state as a solid and ends as Mg2+ in MgCl2, while chlorine starts as Cl0 in Cl2 and ends as Cl− in MgCl2. That clear electron transfer from magnesium to chlorine makes it a redox process. The other forms either aren’t proper chemical equations, or don’t show this electron-transfer clearly. For example, using energy as a reactant isn’t a chemical species and doesn’t depict a redox change; a reaction like MgO + H2 → Mg + H2O does involve redox but is less direct in illustrating the transfer between elemental states to form a stable compound; and simply dissociating MgCl2 into Mg2+ and Cl− in solution shows no change in oxidation state, so it’s not redox.

Redox reactions involve the transfer of electrons, shown by changes in oxidation numbers. In this equation, magnesium starts in the zero oxidation state as a solid and ends as Mg2+ in MgCl2, while chlorine starts as Cl0 in Cl2 and ends as Cl− in MgCl2. That clear electron transfer from magnesium to chlorine makes it a redox process.

The other forms either aren’t proper chemical equations, or don’t show this electron-transfer clearly. For example, using energy as a reactant isn’t a chemical species and doesn’t depict a redox change; a reaction like MgO + H2 → Mg + H2O does involve redox but is less direct in illustrating the transfer between elemental states to form a stable compound; and simply dissociating MgCl2 into Mg2+ and Cl− in solution shows no change in oxidation state, so it’s not redox.

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