(20 pts) Be creative and use the knowledge you have learned in Topic 5 (partition coefficients among air, liquid, solid phases) to answer (and discuss why) the followingCOVID-19 related questions, in less than 400 words: (a) What was the main pathway of transmission, according to CDC, when the pandemic first started? (before May 2020) (b) What is the main pathway of transmission, according toCDC, from most recent news? (between Mar-May 2021) (c) Compare (a) and (b), and known facts, are there changes? If there are, does it surprise you? Why? (d) Is cleaning the environment or surfaces still significant? Discuss based on the partition/eguilibrium theories. (A+ > 20 pts, A > 17 pts, B → 14 pts, C → 10 pts, D → 8 pts)

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