Question

Haemoglobin of the blood forms carboxyhaemoglobin with

• A. CO$_2$
• B. CO
• C. SO$_2$
• D. NO$_2$

Hint:

Carbon monoxide is highly dangerous because it binds strongly with haemoglobin, blocking oxygen transport in the body.

Answer 1

The Correct Option is B

Step 1: Recall that haemoglobin is the oxygen-carrying protein present in red blood cells.
Step 2: Carbon monoxide (CO) has a very high affinity for haemoglobin—about 200–250 times greater than oxygen.
Step 3: When CO binds with haemoglobin, it forms a stable compound called carboxyhaemoglobin.
Step 4: This prevents haemoglobin from carrying oxygen, leading to oxygen deficiency in tissues.
Step 5: Therefore, haemoglobin forms carboxyhaemoglobin with carbon monoxide (CO).