Question: how many moles of carbon dioxide are in 10.0 g of carbon dioxide?
Answer: Assuming carbon has an atomic mass of 12.01 and oxygen of 15.99, the molar mass of CO2 would be 43.99 g/mol. I'll round it to 44 g/mol for convenience. Now divide 10 g by 44g/mol to get 0.22727… moles.