The methane, CO2, and nitrogen was probably boiled out of the rocks that formed the planet.
probably it was a mixture of sulphur dioxide & carbon dioxide, mixed with small fragments of vapour phase of water molecules in the volcanic ash (as predicted)
Earth's atmosphere is 79% nitrogen, 20% oxygen, and the remainder a mixture of other gases; water vapor, CO2, argon, carbon monoxide, methane, and others.
Scientist theorize that bacteria with chlorophyll in them slowly but surely began to multiply. And as they did, they photosynthesized enough to create an entire atmosphere. (as you know oxygen is a byproduct of photosynthesis)
There is still a lot of debate about the source of the gasses in Earth's atmosphere. Scientists have long believed that the stuff on Earth formed with the Earth, and that the water and oxygen have been here all along, bound up in the crust.
But increasingly, astronomers are beginning to speculate that much of the water now on Earth may have arrived with a succession of comets or comet-like bodies that later crashed into the Earth.
At this point, we can't say for certain; keep an open mind!
Most of the gases in the early atmosphere came from the many volcanos on the surface of the earth
Initially it was just gravity, reduced by the moon forming collision, and then modified by plants (making oxygen from water).
It came from very simple organisms that produced oxygen. These organisms came to this planet from outer space by asteroids.
Ammonia, Methane, Water Vapor, & Hydrogen.
Probably from comets hitting Earth after it solidified.
Hydrogen, nitrogen, helium
Nitrogen and oxygen, respectively, are the two most abundant gases in the earth's atmosphere.
Hydrogen, Nitrogen, Oxygen
Nitrogen and Oxygen
on ancient Earth, nitrogen, water vapor, carbon dioxide, and methane were probably the most abundant gases in the atmosphere.
mostly carbon dioxide with little or no oxygen.
Nitrogen and oxygen, respectively, are the two most abundant gases in the earth's atmosphere.
Nitrogen & oxygen.
These gases are nitrogen, oxygen, argon, carbon dioxide.
Nitrogen and Oxygen
Hydrogen, Nitrogen, Oxygen
The most of the mass of atmosphere is contained in troposphere. It contains most gases.
These gases are nitrogen, oxygen and argon.
on ancient Earth, nitrogen, water vapor, carbon dioxide, and methane were probably the most abundant gases in the atmosphere.
Gases of the atmosphere were attracted by gravity from the space.
Nitrogen and Oxygen make up nearly 99% of the dry atmosphere.
These gases are: nitrogen (78,084 %), oxygen (20,9476 %), argon (0,934 %), carbon dioxide (0,0314).
mostly carbon dioxide with little or no oxygen.