Teachers Notes:

Problem 1:
2Mg(s) + O₂(g) → 2MgO(s), synthesis reaction

Problem 2:
3Mg(s) + N₂(g) → Mg₃N₂(s), synthesis reaction

Problem 3:
2 Mg(s) + CO₂(s) → 2 MgO(s) + C(s), single-replacement reaction

Problem 4:
Mg(s) + H₂O(g) → MgO(s) + H₂(g) , single-replacement reaction

Problem 5:
No water should be used to put out a magnesium fire. When heated water becomes steam, which reacts with magnesium producing hydrogen. The hydrogen can explode and produce balls of fire.

Problem 6:
No a carbon dioxide fire extinguished would not work because magnesium still burns in the presence of carbon dioxide.

Problem 7:
MgC_l2 (s) → Mg (s) + C_l2(g), decomposition