Question

Suggest a reason as to why $CO$ is poisonous.

Answer 1

CO is very toxic as it can form complex with haemoglobin in the red blood cells. Haemoglobin combines with oxygen to form oxyhaemoglobin
$Haemoglobin+O_2\rightleftharpoons Oxyhaemoglobin$
Oxyhamoglobin (formed in lungs) is carried to different cells where it gives its oxygen. CO has stronger affinity for Haemoglobin than oxygen. Due to this, the oxygen carrying capacity of blood is destroyed.. This results in suffocation and finally death.