What type of terrestrial sediments began to form as atmospheric oxygen level rose late in the Proterozoic? A- Black shale B- Oolitic limestone C- Chert D- Redbeds of soil

The continental Redbeds of soil in South AFRICA was aged by 1.9 billion years indicate that the atmospheric Oxygen at that time was that of the modern level A- 15 perecent B- 30 percent C- 70 percent D- 25 percent

How did Earth's atmosphere become oxygen-rich?A.Biological activityB.Volcanic outgassingC.Ozone depletionD.Tectonic movementSUBMITarrow_backPREVIOUS

Which gas formed a major part of the early atmosphere?Carbon dioxideNitrogenMethaneAmmonia2The early atmosphere contained a large amount of water vapour. What happened to this?It condensed to form the oceansIt evaporated into spaceIt was used by plants for photosynthesisIt was used by animals for respiration3Which process has reduced the levels of carbon dioxide in the atmosphere to the low levels we have today?Formation of sedimentary rocksAll of theseFormation of fossil fuelsPhotosynthesis4The levels of methane and ammonia in the early atmosphere decreased over time, while the level of nitrogen increased. What is the best explanation for this?Human activities such as burning of fossil fuels and farmingMethane and ammonia are unreactive, while nitrogen reacts with oxygenMethane and ammonia react with oxygen, while nitrogen is unreactivePlants absorb methane and ammonia, and they produce nitrogen5Which two gases together form approximately 99% of the modern atmosphere?Nitrogen and oxygenNitrogen and hydrogenOxygen and hydrogenOxygen and carbon dioxide6Approximately what percentage of carbon dioxide is found in the modern atmosphere?0.9%0.004%1%0.04%

(Q002) The Earth's atmosphere  began as nitrogen and oxygen, left over from the solar nebula.  acquires its carbon dioxide from photosynthesis by green plants.  gets warmer as its carbon dioxide concentration goes down.  became more oxygen-rich during the Proterozoic, after the evolution of photosynthetic organisms in the Archean

Chose the correct statement(s)(a) A very thin envelope of gases that surrounded the earth at the time of its formation.(b) About 600 billion years ago plants and animals were formed on the Earth.(c) The two probable sources of oxygen in the atmosphere are photodissociation of watermolecule and evapotranspiration.(d) The evidence of oxygen in the ocean is noted between 2.5 and 3.0 billion years ago.(a) and (b)(b) and (c)(c) and (d)(a) and (d)