Answer:
The formula tells us that each mole of CaCO3 contains 3 moles of Oxygen. Then 3 moles of CaCO3 would contain 3 X 3 or 9 moles of Oxygen. I mole is define as avogadro’s number of units. Avogadro’s number is 6.02 X 10^23. so the answer is 3 X 3 X 6.02 X 10^23. = 5.42 X 10^24