Difference between primitive and modern atmosphere.
Answers
Explanation:
For decades, scientists believed that the atmosphere of early Earth was highly reduced, meaning that oxygen was greatly limited. Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia.
Answer:
The primitive atmosphere of earth was reducing atmosphere with little or no oxygen but was rich in water vapour, carbon monoxide, carbon dioxide, nitrogen, and hydrogen. The UV and gamma radiations from Sun were the major sources of energy for chemogenesis as these radiations have energy quanta that can release electrons from atoms resulting in formation of highly reactive free radicals which in turn combined to form early organic compounds. The ozone layer of present day atmosphere absorbs these UV and gamma rays. Owing to immense long lasting rainstorms, tremendous amount of lightening was generated. Lightening provided energy for chemical reactions between hydrogen and free oxygen, nitrogen and carbon to form water (present in form of superheated steam due to high earth temperature), ammonia, methane and cyanides. The evolution of photoautotrophs from chemoautotrophs led to accumulation of oxygen in atmosphere and thus, ozone layer was formed much later during evolution