Consider a person who is infected with the coronavirus. In a completely empty field, this person has been standing still for quite some time. There's no wind blowing on this day, and during this entire period, no coronavirus reproduces or perishes. We label the coronavirus as species A, while species B corresponds with the air. We will focus just on the person's head, treating it as a ball-like object whose radius is R: We will describe it in spherical coordinates, while neglecting all angular dependence of this transport process. Importantly, the density of the coronavirus in the vicinity of the person's head is always Ph. Besides, take a look at the schematic which is provided. Importantly, here is the general equation for the Mass Balance: -A+TA= a at PA Eqn. 1 Here is also a general equation for the Mass Flux, which notably employs Fick's "Law": = TA-DABPVWA+PA Eqn. 2 a. Why are quotation marks often used in the context of Fick's "Law"? b. Make the usual assumptions for mass transfer so that you can describe this transport process in the most rudimentary way. Make sure that all assumptions are clearly stated in the box below (incorporate extra assumptions as you proceed through the solution).