According to the Law of Conservation of Mass, the total mass of reactants must equal the total mass of products.
In this reaction, we have:
- 2 grams of potassium (K)
- 5 grams of oxygen (O)
Total mass of reactants = 2 grams (K) + 5 grams (O) = 7 grams
Since potassium oxide (K2O) is the product of this reaction, the mass of the potassium oxide produced will also be 7 grams.
Therefore, the correct answer is:
7 grams