First, you convert liters to moles.
Usually you have to go to grams but this is STP.
Get moles directly by dividing the 4 by STP (22.4)

About

or 0.18 moles whichever your teacher prefers
Answer:
It is used as a catalyst.
to be in kg/mL. What you need to do first is write 22.4 kg/L over 1. Divide this by 1000 because there are 1000 mL per L. Your equation will look like 22.4 kg/L over 1 divided by 1000/1. You end up getting .0224 kg/mL.
Enyzmes speed up all chemical reactions
(Just took an AP Bio test with this question on it)