1. The problem statement, all variables and given/known data If you have 4.5 x 1020 molecules of SnO2, how many moles of O do you have? 3. The attempt at a solution I'm really getting the hang of moles lately but what is bothering me in this question is 4.5 x 1020 molecules of SnO2. If it was one molecule, you would have 2 moles of O yes? Therefore in 4.5 x 1020 molecules, you have 4.5 x 1020 multiplied by 2? But that doesn't give me the correct answer.