a volatile organic solvent is evaporating as it falls through stagnant air. the radius of the drop is 2 mm. assume that the rate of evaporation is proportional to the change in surface area, which can be simplified for this drop as 10r2. the volume of this droplet can also be expressed as 3r3. the density of the solvent, 0.8 g/cm3, does not change over time. the evaporation rate can be expressed as: evaporation rate=5(surface area) (in/s) a.) define the system. b.) find an expression that predicts the droplet radius as a function of time. (hint: you will need to use the chain rule to simplify this expression). c.) how long will it take for the volume of the droplet to be reduced to half of its initial value