Which of the following is the correctly balanced equation for the reaction of magnesium with oxygen to form magnesium oxide?

Step-by-step solution

1. Write the unbalanced equation: $\text{Mg}+{\text{O}}_2\to \text{MgO}$.
2. Count the atoms on both sides: left has 1 Mg and 2 O; right has 1 Mg and 1 O.
3. Balance oxygen by placing coefficient 2 before MgO: $\text{Mg}+{\text{O}}_2\to 2\text{MgO}$, which now gives 2 Mg on the right.
4. Balance magnesium by placing coefficient 2 before Mg on the left: $2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$.
5. Verify that both sides have 2 Mg atoms and 2 O atoms; the equation is balanced.

Concept tested: Balancing chemical equations

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