11. The following are the common sources of methane, EXCEPT:
A trees
B. garden waste
C. cloth
D. volcanoes
12. Which of the following element is the most abundant in the Earth's atmosphere?
A. Argon
B. Carbon dioxide C. Nitrogen
D. Oxygen
13. Why is ozone above the troposphere essential?
A. It warms Earth's surface.
C. It makes jet flying more comfortable.
B. It helps in cloud formation.
D. It offers protection from harmful UV rays.
14. Why was the use of chlorofluorocarbons banned all over the world?
A. It depletes the stratosphere.
C. It depletes the ozone layer.
B. The atmosphere is unstable.
D. The atmosphere will be too cold.
15. Clara noticed that her plants are not growing healthy. She suspects that the temperature in their area is too hot.
So, she decided to make a greenhouse for her plants. Is Clara's decision right in making a greenhouse?
A. Yes, because the increasing temperature will ruin the plants.
B. Yes, because the increasing temperature will not ruin the plants.
C. No, because the greenhouse does not affect the plants.
D. No, because the greenhouse has a bad effect on the plants.​