answer
0.37946 moles
explanation
at STP, there are 22.4 liters for every mole of gas, so divide the number of liters by 22.4 to find the number of moles
number of moles = [tex]8.5 liters * \frac{1 mole}{22.4 liters}[/tex]
number of moles = 0.37946 moles