Answer:
2. the reaction will shift to the left
Explanation:
Hello,
By means of the Le Chatelier's principle, when adding a product, the inverse reaction is favored as the products are now considered as reactants, thus, since magnesium oxide is a product for the given chemical reaction, and in addition, it is being added, the equilibrium will shift leftwards, thus, the answer is:
2. the reaction will shift to the left
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