Gases In The Early Atmosphere

Question 1

4.6 billion years ago- what gases and why?

Answer 1

Hydrogen and helium
Volcanic activity
Produced carbon dioxide, methane and little or no ammonia

Question 2

4 billion years ago

Answer 2

Carbon dioxide, water and nitrogen
Volcanic activity released water vapour condensed to form oceans
Bacteria and algae evolved and used co2 to make food for themselves and produce oxygen

Question 3

2.7 billion years ago

Answer 3

First molecules oxygen appear
Plants evolved, carbon dioxide decreased as was part of photosynthesis which produced more oxygen
Poisonous gases reacted with oxygen and disappeared

Question 4

200 million years ago

Answer 4

Today’s atmosphere- 
78% nitrogen 
21% oxygen 
0.9 % argon 
0.04% Carbon dioxide
Oxygen enabled plants and animals to evolve, taking in oxygen and  giving out co2 (respiration) 
Plants photosynthesis 
Keep atmosphere in balance

Question 5

Today

Answer 5

Same as 200 million years ago

Question 6

Today and the future

Answer 6

Burning fossil fuels increases carbon dioxide levels in atmosphere faster than it can be removed
Cutting down trees less Co2 being used in photosynthesis