Nitrogen.
This gas is nitrogen.
argon?
Oxygen was the least plentiful gas in Earth's early atmosphere. The atmosphere primarily consisted of carbon dioxide, water vapor, nitrogen, and small amounts of other gases. Oxygen levels rose significantly over time due to the process of photosynthesis by early life forms.
that sounds unanswerable.
Everywhere, at least on earth and in the earths atmosphere.
argon
At 0.3%, carbon dioxide is the least common gas in the Earth's atmosphere. This is in no way indicative of its lack of importance, since carbon dioxide is the primary source of life on earth and its concentration on earth's pre-industrial atmosphere has been regulated by photosynthetic organisms and is a principle supplier of greenhouse gases.
This Question has not been answered yet. Genesis Roxx[:
Oxygen was least likely to have been a component of Earth's atmosphere before life began. It was initially scarce, and the atmosphere was primarily made up of gases such as methane, ammonia, water vapor, and carbon dioxide. Oxygen started to accumulate in the atmosphere following the emergence of photosynthetic organisms.
The Earth's crust is the least dense layer. It is made up of rocks like granite and basalt and is relatively thin compared to the other layers of the Earth.
The outer core, inner core, mantle, crust, water, atmosphere. This is the order from densest to least dense.
oxygen