Magnesium reacts with oxygen to give:

Options

A. `MgO_2`
B. `MgO`
C. `Mg_2 O`
D. `Mg(OH)_2`

Explanation

To determine the product of the reaction between magnesium and oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The two reactants in this reaction are magnesium (Mg) and oxygen (O).

2. **Determine the Valency**:
- Magnesium (Mg) is a metal that typically loses two electrons, resulting in a +2 charge. Therefore, its valency is +2.
- Oxygen (O) is a non-metal that typically gains two electrons, resulting in a -2 charge. Therefore, its valency is -2.

3. **Write the Chemical Symbols**:
- For magnesium, the symbol is Mg.
- For oxygen, the symbol is O.

4. **Combine the Elements Using the Criss-Cross Method**:
- To combine these elements, we can use the criss-cross method. We take the valency of magnesium (+2) and place it as a subscript for oxygen, and the valency of oxygen (-2) and place it as a subscript for magnesium.
- However, since both valencies are the same in magnitude (2), the formula simplifies to just MgO.

5. **Write the Final Chemical Formula**:
- The final product of the reaction between magnesium and oxygen is magnesium oxide, which is represented by the chemical formula MgO.

### Final Answer:
Magnesium reacts with oxygen to give magnesium oxide (MgO).

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