Question

How did the original reducing atmosphere of primitive earth change?

Answer 1

Hint: An atmospheric condition in which oxidation is prevented by the removal of oxygen and other oxidizing gases or vapours is known as a reducing atmosphere is. This condition may contain actively reducing gases such as hydrogen, carbon monoxide, and gases such as hydrogen sulfide that would be oxidized by any present oxygen.

Complete answer:
The atmospheres of planets in the solar system are the composition of various gases, particulates, and liquids. They also serve as the dynamic places that affect redistribution of heat as well as other forms of energy. On Earth, the atmosphere provides a critical abiotic component for proper growth and survival of the living things.
At the time of its formation, the atmosphere of the Earth is generally believed to have been reducing. This concept was first proposed by Oparin and further it is discussed by Urey. The concept of primitive earth refers to the atmospheric conditions of the newly formed earth.
This atmosphere of primitive earth mostly contained methane, nitrous oxide with a little quantity of ammonia, water, and hydrogen. Only ammonia would have been found because it is soluble in water. UV light and electric discharges were considered as sources of energy for amino acid synthesis. Electric discharges were the most efficient source, although most other sources of energy produce amino acids.
Due to the prebiotic synthesis of amino acids, eleven types of amino acids were identified, four of which present in proteins. Hydroxy acids, simple aliphatic acids, and urea were also identified at the synthesis of amino acids. These experiments have been repeated recreated in the laboratory conditions which revealed the identification of about thirty-three different types of amino acids.
Methionine synthesis can be occurred by electric discharges if $H_{2}S$ or $C{H}_{3}SH$ is added to the reduced gases. Eighteen types of amino acids have been identified in the Murchison meteorite which is a type II carbonaceous chondrite. Among these eighteen amino acids, six are present in proteins. All of the amino acids which are observed in the Murchison meteorite have been found among the electric discharge products.

Note: Primitive earth refers to the earth of that time when it is formed. The Earth formed approximately four billion years ago, along with the formation of other planets in the solar system. As the Earth was cool during its formation, a primitive atmosphere was created by the gasses that produced from the early volcanoes. The early atmosphere of the earth did not contain oxygen as an important gas.