the atmosphere

Question 1

what happened in phase 1 ?

Answer 1

molten because of volcanoes

then it cooled and a thin crust formed

mostly CO2 and water vapour

water vapour condensed to form ocenas

Question 2

how were oceans formed?

Answer 2

water vapour condensed

Question 3

what happened in phase 2 ?

Answer 3

early CO2 dissolved into oceans

nitrogen put into atmosphere

green plants evolved
they removed CO2 and produced oxygen (photosynthesis)

Question 4

what happened in phase 3?

Answer 4

build up of oxygen killed early organisms

allowed evolution of complex organisms

oxygen created ozone layer which blocks harmful rays from the sun

Question 5

how much nitrogen is in todays atmosphere?

Answer 5

78%

Question 6

how much oxygen is in todays atmosphere?

Answer 6

21%

Question 7

how much CO2 / other gases is in todays atmosphere?

Answer 7

less than 1%

Question 8

what is the ozone layer?

Answer 8

protects against sun rays

Question 9

how does the greenhouse effect work?

Answer 9

greenhouse gasses in the atmosphere let sun radiation pass through which heats the earth