Haemoglobin is a respiratory pigment in RBCs. It is tetrameric conjugated protein. It consists of two parts: haem and globin. Haem is the non-protein part and made up of iron or ferrous (Fe++) containing perphyrins.
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Carbon monoxide is highly poisonous gas. It is a colourless and odourless gas and hence its presence cannot be detected immediately. When inhaled, carbon monoxide readily combines with the haemoglobin of our blood.
Carbon dioxide is not normally considered a pollutant because it is a normal constituent of air. However, excess of carbon dioxide is considered a [pollutant because it leads to adverse effects on the environment.
Modern human activities are responsible for release of huge quantities of CO2 in the atmosphere. The major activities, which contribute towards this, are burning of fossil fuels and cultivation of soil.
Though carbon dioxide is present in very small proportion (0.03%) in the atmosphere, it performs very important functions as mentioned below:
All fossil fuels on burning produce carbon dioxide gas. Carbon dioxide is not a poisonous gas. The presence of carbon dioxide in our atmosphere is essential for plant life. But, increase in the concentration of carbon dioxide in the atmosphere leads to an increase in the temperature in the earth.
When the fossil fuels are burnt in a limited amount of air (oxygen), the products of combustion are CO and H2O. Carbon monoxide is the most dangerous air pollutant. Carbon monoxide when inhaled combines with hemoglobin in the blood to form carboxyhaemoglobin. Carboxyhaemoglobin cannot carry oxygen.
To gain stability, it should lose its valence electrons, gain four more electrons or share its 4 valence electrons with other atoms. Carbon atom has been no tendency to lose its four valence electrons or gain four more electrons from other atoms.
A carbon atom has four electrons in its outermost valence shell. So, it needs four more electrons to complete its octet. A carbon atom completes its octet only by sharing its valence electrons with other atoms.
In this reaction, the mass number remains constant (at 14),. So, the sum of the number of protons and neutrons remains constant.