Answer:
12 grams
Explanation:
2Mg + O₂ → 2MgO
This means that 2 moles of Magnesium reacts with 1 mole of Oxygen gas to form 2 moles of Magnesium Oxide (refer to Gay Lussac's law i.e when gases react they do so in volumes that bear a simple ratio to one another and to the products formed (in gaseous state) provided that temperature and pressure are kept constant)
Thus, 12g of Mg = 12g of MgO because the mole ratio of Mg to MgO is 2:2
