Chemistry Of The Atmosphere

Question 1

How long have the proportions of the gases in the atmosphere been like today

Answer 1

200 million years

Question 2

What are the gases found in today’s atmosphere (5)

Answer 2

Nitrogen,oxygen,carbon dioxide,water vapour,noble gases

Question 3

What are the percentages of the gases in today’s atmosphere

Answer 3

Nitrogen = 80% Oxygen = 20% Other gases = <1%

Question 4

What timescale is evidence for the early atmosphere limited too

Answer 4

4.6 billion years ago

Question 5

What theory is given for the earth’s early atmosphere

Answer 5

1. First billion years intense volcanic activity released lots of CO2 and water vapour 2. When the earth cooled the water vapour condensed to form oceans 3. Over time carbon dioxide levels started to decrease 4. Algae and plants evolved 5. Oxygen levels started to increase and animals were able to evolve

Question 6

What planet is the earths early atmosphere suggested to be like

Answer 6

Mars and Venus, consisting mainly of carbon dioxide and little to no oxygen

Question 7

What other gas was released by volcanoes

Answer 7

Nitrogen N2,methane CH4,ammonia NH3

Question 8

What are the four ways carbon dioxide levels were reduced

Answer 8

1. Dissolved into oceans 2. Plants took it in for photosynthesis 3. Carbonates precipitated producing sediments 4. Locked in fossil fuels

Question 9

How did the percentage of oxygen increase in the early atmosphere

Answer 9

Algae and plants released it during photosynthesis

Question 10

What useful substances have been formed as carbon dioxide decreased (4)

Answer 10

Limestone,coal,crude oil,natural gas

Question 11

Examples of greenhouse gases

Answer 11

Water vapour = H2O, carbon dioxide = CO,methane = CH4