Final answer:
The work done during a normal breath, with a lung expansion of 0.50 L against an external pressure of 1.0 atm, is approximately 50.65 J, which does not match any of the provided answer choices.
Step-by-step explanation:
The work done by our lungs during a normal breath can be calculated using the formula W = P∆V, where P is the external pressure and ∆V is the change in volume. Since the pressure is 1.0 atm and the change in volume is 0.50 L during a normal breath, we convert the volume into liters and use the conversion factor 101.3 J for 1 L⋅atm:
W = (1.0 atm)(0.50 L)(101.3 J/L⋅atm) = 50.65 J
Therefore, the correct answer is none of the provided choices, the actual work involved in this process is roughly 50.65 J.