Question: how many moles of carbon are in 5.2 moles of c7h18?
Answer: In 5.2 moles of C7H18 there are 7*5.2 moles of carbon which is 36.4. This is because for every molecule C7H18 there will always be 7 carbons. So if we have 6.02*10^23 molecules, we will have 7*6.02*10^23 carbon atoms.