Final answer:
The most accurate combination of gases to check the linearity of an oxygen analyzer during exercise would be 100% oxygen and nitrogen, as they can create varying known concentrations without chemical interference, making them suitable for checking linearity. so, option b is the correct answer.
Step-by-step explanation:
To check the linearity of an oxygen analyzer used for exhaled gas analysis during exercise, the most appropriate combination of gases would involve one known concentration of oxygen and another inert or different gas that does not interfere with the oxygen measurement. Therefore, the correct answer is b) Room air and carbon dioxide. Room air contains a known concentration of oxygen (approximately 21%), and carbon dioxide can be used to simulate the change in concentration due to exhalation, but it is not the best choice due to its potential interference with oxygen measurements. A more appropriate combination might be 100% oxygen and nitrogen because they can create varying known concentrations without chemical interference, making them more suitable for checking linearity.
A gas such as nitrous oxide or argon would not be as effective since these gases do not directly relate to the measurement of oxygen concentration in breathing exercises. Helium and methane would also not be suitable as they could potentially affect the analyzer's reading of oxygen levels due to their own unique properties. In medical laboratories, calibrating gas mixtures for oxygen analyzers typically consists of oxygen, nitrogen, and sometimes CO2 in specific proportions to simulate physiological conditions.