C1 Topic 1 edexcel

Question	Answer
Where did the gases that formed the Earths early atmosphere come from?	Volcanic activity
How much oxygen was present in the Earths early atmosphere?	Little/none
How much Carbon Dioxide was present in the Earths early atmosphere?	lots (18%)
Name 4 other gases present in the Earth’s early atmosphere.	Nitrogen, ammonia, methane, water vapour
How do scientists use rocks to work out the composition of the Earth’s early atmosphere?	Analyse the minerals in them and look for oxides.
How do scientists believe the oceans were formed?	Condensation of water vapour
Describe two ways that the carbon dioxide levels in the early atmosphere were reduced.	It dissolved in oceans and was locked up in sedimentary rocks
What mineral is limestone made from?	Calcium Carbonate
How did photosynthesis affect the composition of the atmosphere?	Removed Carbon Dioxide, added Oxygen
What is the current composition of the Earths atmosphere	Nitrogen 78% Oxygen 21% Argon 0.9% Carbon Dioxide 0.04% other trace%
State 3 ways humans changed the composition of the atmosphere.	Burning fossil fuels, farming, deforestation
What 2 main gases do volcanoes release in to the atmosphere	Nitrogen and Carbon dioxide
What effect does deforestation have on the amount of carbon dioxide in the atmosphere, explain	Increases it as trees are no longer able to remove carbon dioxide through photosynthesis.

Resource summary

	Created by Princess Terin about 8 years ago