Question

Describe the percent composition of all gases in the atmosphere. Which is the greatest?

Answer 1

Nitrogen (78%) and oxygen (21%) are the two most abundant gases.

Explanation:

Earth's atmosphere has changed and evolved over long periods of geological time. Nitrogen was originally derived from volcanic eruptions around 4 billion years ago. Oxygen on the other hand, was derived almost entirely from plant photosynthesis and this did not happen until about 2.5 billion years ago.

Small amounts of trace gases are also found in the atmosphere. However, CO2 as a trace gas is increasing rapidly from human burning of fossil fuels and burning forests and is contributing to global climate change. Methane and nitrous oxide are other powerful greenhouse gases that are also increasing due to human activities.