Breathing air that contains 4.0% by volume CO2 over time causes rapid breathing, throbbing headache, and nausea, among other symptoms.
a. What is the concentration of CO2 in such air in terms of mol percentage?
b. What is the concentration of CO2 in such air in terms of molarity, assuming 1 atm pressure, and a body temperature of 37 C?
Express your answers using two significant figures.