Question

Which of the following has greater affinity for haemoglobin in blood?

• A. $CO$
• B. $O_2$
• C. $C{O}_2$
• D. All of these have similar affinity

Answer 1

The correct option is A $CO$

CO has greater affinity for haemoglobin than oxygen and carbon dioxide. When it is inhaled, CO binds to haemoglobin to form carboxyhemoglobin, which is about 300 times more stable than the oxygen-hemoglobin complex. When the concentration of carboxyhemoglobin reaches about 3–4 percent, the oxygen carrying capacity of blood is greatly reduced which may lead to fatal.