What is the atmosphere?
All living organisms
The solid part of the Earth
All water on Earth
The layer of gases surrounding the Earth
Which gas is most important for human respiration?
Carbon dioxide
Hydrogen
Oxygen
Nitrogen
What is the greenhouse effect?
The movement of air across the Earth
The trapping of heat by gases in the atmosphere
The cooling of the Earth’s surface
The formation of clouds
Where does most weather occur?
Thermosphere
Mesosphere
Troposphere
Stratosphere
How can human activities affect the atmosphere?
By altering its composition through pollution
By reducing all gases
By stabilizing all natural processes
By stopping weather patterns
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