Oxygen is needed to carry out a lot of biochemical processes in the body. If the amount of oxygen available to the blood decreases significantly a lot of things will go wrong in the body. For instance, lack of adequate oxygen will lead to the death of neurons which will eventually leads to brain cells death and irreparable brain damage. Oxygen is also needed for cellular respiration, without respiration, there will not be oxygen for carrying out various cellular activities and this will result into death. Oxygen deprivation will also leads to difficulty in breathing and other associated problems.
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Answer:
C. They don't react with other elements to form compounds
Explanation:
The elements in Group 18 of the periodic table are called "inert", or noble gases.
These elements have their valence shell (the outermost shell of the atom) full of electrons, so they do not gain/give off electrons, and therefore, they do not react with other elements, so they do not form compounds.
In fact, normally the elements try to gain/give off electrons in order to fullfill their outermost shell (the valence shell). For instance, an atom that has 1 electron only in its valence shell, try to "give away" this electron in order to have its outermost shell completed. On the other hand, an atom which has 7 electrons in its valence shell tries to "gain" one electron in order to fullfill the valence shell.
Noble gases, instead, have already 8 electrons in their valence shell, so their valence shell is already completed, therefore they do not react with other elements, and therefore they are called "inert".
