Question 3 options: how many moles of argon atoms are present in 11.2 l of argon gas at stp?

It is known that at if a gas is identified to be as ideal gas then, at STP, the volume of 1 mole of that gas is equal to 22.4 L. Using this fact and the given volume in this item, we determine the number of moles as that below.

                n = (11.2 L of argon)(1 mol argon / 22.4 L of argon)

                 n = 0.5 moles

0.5 moles 

i just got this problem. it's 90.3