Question

Choose the correct answer from the alternatives given.
Which of the following gases forms the most stable compound with haemoglobin as erythrocytes?

• A. Oxygen
• B. Carbon monoxide
• C. Nitrogen
• D. Carbon dioxide

Answer 1

The correct option is B Carbon monoxide

The affinity between hemoglobin and carbon monoxide due to stronger binding between the two and is approximately 230 times stronger than the affinity between hemoglobin and oxygen. The affinity of carbon dioxide for hemoglobin is equal to that of oxygen and the binding of the two are determined by differences in partial pressure. Nitrogen binds very poorly with hemoglobin as it is a poor pi-acceptor and sigma-donor especially compared to CO. So, the correct option is 'Carbon monoxide'.