Carbon monoxide (CO) is highly toxic because it has a much higher affinity for binding to hemoglobin than oxygen (O ). Hemoglobin is the protein in red blood cells that transports oxygen from the lungs to the tissues. However, carbon monoxide binds to hemoglobin about 300 times more strongly than oxygen does, forming a stable complex known as carboxyhemoglobin (COHb). When CO binds to hemoglobin, it prevents oxygen from binding, disrupting oxygen delivery to tissues. This leads to symptoms of hypoxia (oxygen deficiency), including dizziness, confusion, and in severe cases, death. The strong binding of CO to hemoglobin is the primary reason for its toxicity. - Option (A) is correct because carbon monoxide binds 300 times more strongly to hemoglobin than oxygen.
- Option (B) is incorrect because CO does indeed bind to hemoglobin, just much more strongly than oxygen.
- Option (C) is incorrect because CO does not form cyanide in the body. Cyanide is a different toxic compound.
- Option (D) is incorrect because CO toxicity does not lead to coagulation of blood. Thus, the correct answer is option (A).