21. The primary cause of acid rain is:

a) Excessive use of fertilizers
b) Combustion of fossil fuels
c) Agricultural runoff
d) Industrial waste
Answer: b) Combustion of fossil fuels

22. Which of the following materials is commonly recycled?

a) Aluminum cans
b) Glass bottles
c) Paper
d) All of the above
Answer: d) All of the above

23. Which of the following is an example of a renewable resource?

a) Coal
b) Oil
c) Wind energy
d) Natural gas
Answer: c) Wind energy

24. The process of removing pollutants from industrial exhaust gases is known as:

a) Filtration
b) Scrubbing
c) Incineration
d) Sedimentation
Answer: b) Scrubbing

25. Which of the following is a primary pollutant in vehicle exhaust?

a) Sulfur dioxide
b) Carbon dioxide
c) Methane
d) Carbon monoxide
Answer: d) Carbon monoxide

26. The “greenhouse effect” refers to:

a) The cooling of the Earth’s atmosphere
b) The warming of the Earth’s atmosphere due to greenhouse gases
c) The decrease in atmospheric carbon dioxide
d) The increase in atmospheric oxygen
Answer: b) The warming of the Earth’s atmosphere due to greenhouse gases

27. Which of the following is NOT a major greenhouse gas?

a) Methane
b) Nitrous oxide
c) Argon
d) Carbon dioxide
Answer: c) Argon

28. Which of the following practices helps to reduce greenhouse gas emissions?

a) Burning fossil fuels
b) Deforestation
c) Using renewable energy sources
d) Increasing industrial production
Answer: c) Using renewable energy sources

29. The term “eutrophication” describes the:

a) Process of excessive nutrient enrichment in water bodies
b) Loss of biodiversity in ecosystems
c) Increase in carbon dioxide levels
d) Decrease in soil fertility
Answer: a) Process of excessive nutrient enrichment in water bodies

30. Which of the following is a non-renewable resource?

a) Solar energy
b) Wind energy
c) Coal
d) Biomass
Answer: c) Coal