Breathing air that contains 4.0% by volume CO2 over time causes rapid breathing, throbbing headache, and nausea,

Question:

Breathing air that contains 4.0% by volume CO2 over time causes rapid breathing, throbbing headache, and nausea, among other symptoms. What is the concentration of CO2 in such air in terms of
(a) Mol percentage,
(b) Molarity, assuming 1 atm pressure and a body temperature of 37 °C?