Why is air considered to be an earth resource?

how did oxygen originate on earth?

explain how the oxygen and carbon-dioxide cycles on earth are related.

describe how air can be polluted by both natural processes and human activities.

Air is considered to be an earth resource because , as clean air move across in the troposphere Earth;s surface collects bother naturally and manmade pollutants. The planet earth did not carry an oxygen atmosphere from the beginning. Though oxygen could arise from radiation mediated water splitting, these processes were not efficient enough to create a global gas atmosphere. Oxygen in the latter is a product of the photosynthetic activity of early green organisms. Only after biological mass-formation of oxygen the UV-protective ozone layer could develop, then enabling life to move from water onto land. This took billions of years. The basics of the processes of biological oxygen liberation and utilization are described in the following as well as the importance of their steady state equilibrium. Also a hint is given to oxygen as a toxic compound though being a chemical prerequisite for aerobic life on earth. They are related because it is a cycle of gas which an organism need in order to survive for example: a coconut tree inhaled carbon dioxide that comes from animals , they need it in order for photosynthesis they also give off oxygen that we also need. Humans pollute everything. But with the air, Co2 is a major problem. It creates a greenhouse gas effect and creates global warming. We have also used CFC's for our fridges which devastated the ozone layer. Naturally, the only problem is natural disasters like a volcano eruption.also need.  

A) It is considered to be an earth resource because its necessary for all life forms to live.
B) 2.4 billion years ago when the Great Oxidation Event (GOE) occurred. This seemingly sudden jump in oxygen levels was almost certainly due tocyanobacteria– photosynthesizing microbes that exhale oxygen.
C) Trees need carbon dioxide to make oxygen and we need oxygen to make carbon dioxide
D) Human Activities such as
1. Household and Farming Chemicals
2. Burning Fossil Fuels
3. Emissions from industries and manufacturing activities.
Natural events that pollute the air include forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds and natural radioactivity.Pollution from natural occurrences is not very often.

The reflection of the candle in the concave mirror formed an upside-down virtual image that is smaller than the candle.in other words. the answer is the third option, c