Carbon dioxide and global warming: the greenhouse effect
3 marks · EasyThe greenhouse effect is important for life on Earth.
Explain what is meant by the term 'greenhouse gas'.
State why carbon dioxide, but not nitrogen, is a greenhouse gas.
Give one way in which human activities have increased the amount of carbon dioxide in the atmosphere.
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(a) A greenhouse gas absorbs infrared radiation and traps heat in the atmosphere
(b) CO2 can absorb infrared because its vibrating molecule changes polarity, nitrogen cannot
(c) Burning fossil fuels
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Marking points
B1 (a) · 1 mark · Defines greenhouse gas as a substance that absorbs infrared radiation and traps heat in the Earth's atmosphere.
B1 (b) · 1 mark · States (CO2 absorbs infrared as polarity changes when vibrating; N2 does not because no change in polarity).
B1 (c) · 1 mark · States one human activity that increases CO2, e.g., burning fossil fuels, deforestation.
Worked solution
a) A greenhouse gas absorbs infrared radiation and helps trap heat in the atmosphere.
b) Carbon dioxide's vibration changes polarity so it absorbs IR, nitrogen's does not.
c) Humans contribute to increased CO2 by burning fossil fuels or by deforestation.