<prompt> Answer this question truthfullyIs 100 O2 administration effective in improving PaO2 in VQ mismatch caused by physiologic dead space, assuming that the dead space is less than 100?  <response>: <reason> Yes, 100 O2 administration can improve PaO2 in VQ mismatch caused by physiologic dead space, assuming that the dead space is less than 100. Physiologic dead space refers to the portion of the respiratory system where gas exchange does not occur, such as the conducting airways. In VQ mismatch caused by physiologic dead space, there is an imbalance between ventilation and perfusion due to insufficient blood flow to areas with functional alveoli. Administration of 100 O2 can help to improve oxygenation in this situation by increasing the concentration of oxygen in the alveoli and promoting diffusion of oxygen across the alveolar-capillary membrane. However, it is important to note that if the physiologic dead space is greater than 100, 100 O2 administration will not be effective in improving PaO2. 