ATMOSPHERE

Question 1

what % of the atmosphere is nitrogen

Answer 1

78%

Question 2

what % of the atmosphere is oxygen

Answer 2

21%

Question 3

name some other gases in earth’s atmosphere

Answer 3

carbon dioxide
water vapor
argon

Question 4

explain the role of volcanoes in the evolution of today’s atmosphere

Answer 4

volcanoes released water vapor as the earth cooled the water vapor condensed to form our oceans

volcanoes also released huge amounts of carbon dioxide

also, release nitrogen which builds up in the atmosphere

also, release small amounts of methane and ammonia

Question 5

when there was little oxygen and mainly carbon dioxide what planets was the earth’s atmosphere most like

Answer 5

mars

venus

Question 6

state the difference between the early atmosphere and todays

Answer 6

• there is more nitrogen in today’s atmosphere
• the early atmosphere contained large amounts of carbon dioxide but today there is only a small amount
• the early atmosphere contained very little oxygen but today it makes up 21% of the atmosphere

Question 7

how did the amount of carbon dioxide in the atmosphere decrease

Answer 7

• the oceans
  (some of the carbon dioxide in the atmosphere is dissolved in the oceans to form a weak acid. this reacted with minerals in the sea to form precipitates)
• overtime this formed sediments of carbonate rock on the sea bed
• some of the carbon dioxide was used to make corals and shells of organisms (mussels) and when they die they form the SEDIMENTARY ROCK LIMESTONE
• plants take in carbon dioxide during photosynthesis so the carbon is trapped in fossil fuels causing the level of carbon dioxide in the atmosphere to fall

Question 8

how did the amount of oxygen in the atmosphere increase

Answer 8

• photosynthetic algae
  (photosynthesis produced oxygen which entered the atmosphere)
  plants evolved