Formation of the Original Atmosphere by Gases

The Earth’s original atmosphere is presumed to have originated from volcanic activity nearly 4.6 billion years ago.
Initially, the atmosphere was primarily composed of methane, ammonia, water vapour, and nitrogen.
These gases erupted through volcanic activity, contributing to the formation of the original atmosphere.
There was very little oxygen, if any, in this early atmosphere.
The lack of oxygen suggests that early life forms must have evolved in an oxygen-free (anaerobic) environment.
Through a process known as outgassing, the trapped gases were released from the Earth’s interior layers.
High levels of carbon dioxide were present in the initial atmosphere, but not as much as in the atmosphere of Venus or Mars.
Much of the Earth’s water came about because of the condensation of water vapour released through outgassing.
Over time, as primitive life forms evolved and photosynthesis developed, the composition of the atmosphere began to change. Plants used carbon dioxide and released oxygen, gradually increasing its proportion in the atmosphere.
Geological evidence also shows the high presence of sulphur dioxide which is likely to have produced ‘acid rain’ reacting with water in the atmosphere.
This early atmosphere, often referred to as a “reducing atmosphere,” wouldn’t have been conducive to human or animal life as we know it today.
Ceremonies like moon rocks and meteorites have provided supporting evidence for these theories.
The process of the Earth’s original atmosphere’s formation facilitated the eventual development of life on Earth.
It’s important to crosscheck these points with the most recent information or textbook for any recent scientific findings or changes.

Please remember, these points are a revision guide; it’s essential to understand each concept thoroughly, rather than just memorising them.