Flashcards
C1 Revision
Flashcards do conjunto (8)
- 1How was Earth's early atmosphere formed?Earth's early atmosphere was formed from gases produced by volcanoes
- 2What gases made up Earth's early atmosphere?Very little oxygen, large amounts of carbon dioxide, water vapour and small amounts of other gases
- 3Why can't we be sure about Earth's early atmosphere?There are different sources of information however not all the evidence leads to the same conclusion meaning it is difficult to know exactly what the early atmosphere was like and how it has changed
- 4How did the condensation of water vapour form oceans?At first the Earth was very hot and there were no oceans. As the Earth cooled, water vapour in the atmosphere condensed forming liquid water which became oceans
- 5How was the amount of carbon dioxide in the atmosphere reduced?Carbon dioxide dissolved in the oceans. Marine organisms used the dissolved carbon dioxide to make calcium carbonate for shells which fell to the sea bed and become part of the sediment when the organisms die. Over millions of years the layers of sediment get pressed together and form sedimentary rock
- 6How did the amount of oxygen in the atmosphere increase?When the Earth cooled and oceans formed, life formed in them and photosynthesis began. This caused oxygen to build up in the atmosphere and in the atmosphere
- 7What is Earth's atmosphere currently made up of?Earth's atmosphere is made up of 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, 0.9% argon and small amounts of other gases. It also contains water vapour but the amount varies
- 8Why is the composition of Earth's atmosphere not constant?•Burning fossil fuels released carbon dioxide and burning coal also released sulphur dioxide
•Farming releases methane
•Deforestation adds carbon dioxide to the atmosphere and means there are less trees to remove carbon dioxide from the atmosphere
•There are also natural causes for changes in the atmosphere, for example volcanoes emit sulphur dioxide and carbon dioxide when they erupt
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- FlashCards sobre C1 Revision, criado por O R em 10-04-2017.
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