1 mol of any gas occupies 22.4L and has 6.02E23 molecules(a molecule would count as one particle).
So 45.0 mL O3/22,400 = ? mol O3 and that x 6.02E23 = ? number molecules.
35.0/22,400 mL = ? mol O2 and x 6.02E23 = ?
15.0/22,400 = ? mol CO2 and x 6.02E23 = ?
25.0/22,400 = ? mol SO3 and x 6.02E23.
But if you will notice all of them are divided by 22,400 and all are multiplied by 6.02E23 so what does that tell you. First, that says you don't need to multiply and divide by all that stuff. That says that the largest number times two numbers that are constant will be the largest value of particles. right?