The assumptions made are: the gas molecules from caesar's last breath are now evenly dispersed in the atmosphere. the atmosphere is 50 km thick, has an average temperature of 15 °c , and an average pressure of 0.20 atm . the radius of the earth is about 6400 km . the volume of a single human breath is roughly 500 ml . perform the calculations, reporting all answers to two significant figures. calculate the total volume of the atmosphere.