21. What is the name of the layer of the Earth’s atmosphere that contains the ozone hole?
a) Stratosphere
b) Troposphere
c) Mesosphere
d) Thermosphere
22. Which gas is responsible for the depletion of the ozone layer in the Earth’s atmosphere?
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Chlorofluorocarbons (CFCs)
23. What is the name of the process by which the Earth’s magnetic field causes charged particles from the Sun to enter the atmosphere near the poles, causing the aurora borealis?
a) Solar wind
b) Aurora borealis
c) Magnetosphere
d) Coriolis effect
24. Which of the following is not a greenhouse gas?
a) Carbon dioxide
b) Nitrogen
c) Methane
d) Water vapor
25. Which of the following is not a source of air pollution?
a) Industry
b) Agriculture
c) Transportation
d) Water vapor
