When magnesium burns in air, compounds of magnesium formed are magnesium oxide and:

Options

A. `Mg_(3)N_(2)`
B. `MgCO_(3)`
C. `Mg(NO_(3))_(2)`
D. `MgSO_(4)`

Answer

To solve the question, "When magnesium burns in air, compounds of magnesium formed are magnesium oxide and:", we need to analyze the reactions that occur when magnesium is burned in air.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When magnesium (Mg) is burned in air, it reacts primarily with oxygen (O2) and nitrogen (N2) present in the atmosphere.

2. **Formation of Magnesium Oxide**:
- The first compound formed is magnesium oxide (MgO). The reaction can be represented as:
\[ 2Mg + O_2 \rightarrow 2MgO \]
- This reaction is exothermic, meaning it releases heat.

3. **Formation of Magnesium Nitride**:
- Magnesium also reacts with nitrogen in the air to form magnesium nitride (Mg3N2). The reaction can be represented as:
\[ 3Mg + N_2 \rightarrow Mg_3N_2 \]
- This reaction is endothermic, meaning it absorbs heat.

4. **Identifying Compounds Formed**:
- From the reactions above, we can conclude that when magnesium burns in air, it forms both magnesium oxide (MgO) and magnesium nitride (Mg3N2).

5. **Conclusion**:
- Therefore, the answer to the question is that when magnesium burns in air, the compounds formed are magnesium oxide (MgO) and magnesium nitride (Mg3N2).

### Final Answer:
When magnesium burns in air, the compounds formed are magnesium oxide (MgO) and magnesium nitride (Mg3N2).

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