Viscosity and Diameter of Co2

Would really like some help with the above question.

For part a), am i correct in assuming it only wants me to just multiply the two numbers together to get this ratio, just seemed a bit simple to me. Unless the temp needs to be changed to kelvin, but still seemed quite painless of a question.

and for b), not really sure what exactly has to be done, it probably leads on from a)? I was thinking about using something from the mean fre parth equation? But The equations ive been thinking of using seem to want an average velocity, which I dont immediatley have. Maybe i can calculate the speed using E=(3/2)(kT) to get the energy and then use that for the velocity? But then I dont know how iI could get the mass as I dont have any amount of moles?

Would just like any pointers in the correct direction to get htis question answered! :smile: