Q. Which of the following gases reduces the oxygen carrying capacity of the blood?
Answer:
Carbon monoxide
Notes: Carbon monoxide (CO) reduces the oxygen carrying capacity of blood. This is because it has a larger affinity towards haemoglobin than oxygen. Haemoglobin is responsible for circulating oxygen. Hence, in the presence of carbon monoxide the haemoglobin bonds with it to form carboxy-haemoglobin rather than the oxygen and hence reduces the oxygen carrying capacity of blood.