Question: how many atoms of oxygen are present in 300 grams of calcium carbonate?
Answer: Explanation: Moles of calcium carbonate, 300⋅g100.09⋅g⋅mol−1 ≅ 3⋅mol . Given the elemental makeup, in such a quantity there are 3 moles of calcium, 3 moles of carbon, and 9 moles of oxygen.