Here's the balanced equation for the reaction of magnesium metal with oxygen gas to produce magnesium oxide:

2 Mg (s) + O₂ (g) → 2 MgO (s)

Explanation:

* Mg (s): Magnesium metal in its solid state.

* O₂ (g): Oxygen gas.

* MgO (s): Magnesium oxide, a solid compound.

Balancing the Equation:

* Magnesium (Mg): There are 2 magnesium atoms on both sides of the equation.

* Oxygen (O): There are 2 oxygen atoms on both sides of the equation.

This equation is now balanced because the number of atoms of each element is the same on both the reactants' and products' sides.