Multiple choice

The most stable product formed with haemoglobin is

  1. CO2

  2. O2

  3. CO

  4. SO2

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carbon monoxide (CO) binds to haemoglobin with approximately 200-250 times greater affinity than oxygen, forming carboxyhaemoglobin. This stable complex is the strongest bond among the options, which is why CO is so toxic.