Nitrogen is most abundant gas in atmosphere while oxygen is second most abundant gas. The nitrogen and oxygen are present in diatomic form such as O₂ and N₂.
Water vapors are also present but the percentage vary according to location. In hot humid areas the percentage of water is 0- 4% and it is third abundant gas.
The percentage of other gases in atmosphere are given below:
Ozone gas is the least abundant gas in the earth's atmosphere. Their concentration is least but it has hue impact on the people and animals living in earth.
Ozone is the the layer which protects the incoming ultraviolet rays from the sun which reaches the earth.
The percentage of ozone gas is 0.000004% in the atmosphere which is very less.
If you are asking to tell the difference between taste cells and olfactory receptors, taste cells are obviously for tasting substances and olfactory receptors are used for smelling.
