Mg-MgO-MgCO3-Mg(NO3)2-Mg(OH)2-MgO

It seems like you have listed a series of chemical compounds involving magnesium (Mg). Here is a breakdown of the compounds you mentioned:

1. Mg: This is the chemical symbol for magnesium, a metallic element with atomic number 12.

2. MgO: This is magnesium oxide, a compound formed by the combination of magnesium and oxygen.

3. MgCO3: This is magnesium carbonate, a compound formed by the combination of magnesium, carbon, and oxygen.

4. Mg(NO3)2: This is magnesium nitrate, a compound formed by the combination of magnesium and nitrate ions.

5. Mg(OH)2: This is magnesium hydroxide, a compound formed by the combination of magnesium, oxygen, and hydrogen.

6. MgO: This is magnesium oxide, which was already mentioned above.

If you have any specific questions or need more information about these compounds, feel free to ask!