Question: how many moles of o2 are needed to react with 60.0g of c8h18?
Answer: How many moles of O2 are needed to react with 60.0g of C8H18 (octane)? How many litres of CO2 are produced? so 60.0/114 x (25/2) = 6.5789 mols. You're allowed 3 s.f. (60.0 has 3) so round to 6.58 mols O2 needed.