Question

Which of the following is a silent killer gas, which combines with haemoglobin in the blood?
A. \[C{O_2}\]
B. \[CO\]
C. \[NO\]
D. \[N{O_2}\]

Answer 1

Hint: All the gases given in the options have adverse effects on human health.Haemoglobin is a protein in red blood cells that transports the oxygen to different parts of the body.A gas which affects the haemoglobin oxygen complex will be the correct option.

Complete step by step answer:
So to find out the correct option we will try to find the gas which combines with haemoglobin in the blood.
The first option (A) is \[C{O_2}\],
-Carbon dioxide is an asphyxiant, in other words, as \[C{O_2}\]levels in a closed room rise, carbon dioxide replaces the oxygen your body needs. It mostly affects your brain. At moderate \[C{O_2}\]levels, around 1000 ppm, there are observable effects on your thinking.
So option (A) can be eliminated as it does not combine with haemoglobin in the blood.
Now we look into the effect of \[NO\] and \[N{O_2}\] on human health.
-When nitrogen is released during fuel combustion it combines with oxygen atoms to create nitric oxide (NO). This further combines with oxygen to create nitrogen dioxide. Nitric oxide is not considered to be hazardous to health at typical ambient concentrations, but nitrogen dioxide can be. Nitrogen dioxide and nitric oxide are referred to together as oxides of nitrogen, mainly impacts on respiratory conditions causing inflammation of the airways at high levels.
So option (C) and (D) can also be eliminated because they also do not combine with haemoglobin in the blood.
Now we look into the effect of \[CO\] on human health
-The highly poisonous nature of \[CO\] arises because of its ability to form a complex with haemoglobin, which is about 300 times more stable than the oxygen-haemoglobin complex. This prevents haemoglobin in the red blood corpuscles from carrying oxygen round the body and ultimately resulting in death.
Carbon monoxide (CO) is a gas that can kill you quickly. It is called the “silent killer.”

Hence option (B) “CO” will be the correct option as it combines with haemoglobin in the blood.

Note:

Carbon monoxide is called the “silent killer” because it is colourless, odourless, tasteless and non irritating. If the early signs of CO poisoning are ignored, a person may lose consciousness and be unable to escape the danger.