Let’s go through each question one by one, step by step.
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Q.9: Which of the following is NOT a cause of water pollution?
We need to find which option does
not pollute water.
- a) Chemical fertilizers and pesticides → These run off into rivers and lakes when it rains → causes pollution.
- b) Mining Activities → Releases heavy metals and chemicals into water → causes pollution.
- c) Oil refineries → Often leak oil or release toxic waste into water → causes pollution.
- d) Afforestation → This means planting trees. Trees help clean air and soil, and actually protect water sources by preventing erosion. It does
not cause pollution — in fact, it helps reduce it.
✔ So, the correct answer is
d) Afforestation.
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Q.10: ________ contain nitrogen and phosphorus. When rainfall washes them into streams and lakes, this results in excessive growth of algae...
This is describing “eutrophication” — too many nutrients (like nitrogen and phosphorus) cause algae blooms.
What contains these nutrients?
- a) Deforestation → Removes trees, but doesn’t directly add nitrogen/phosphorus to water.
- b) Pesticides → Kill pests, not mainly known for adding N/P to water.
- c) Fertilizers → YES! Farmers use them to grow crops. They are full of nitrogen and phosphorus. Rain washes them into water → algae grow too much.
- d) Sewage → Also has some nutrients, but fertilizers are the main source mentioned in textbooks for this process.
✔ Best answer:
c) Fertilizers
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Q.11: Which term is defined as the chemical substance used to kill weeds and insects?
Let’s look at the options:
- a) Deforestation → Cutting down trees → not a chemical.
- b) Pesticides → Yes! “Pesti” = pest, “cide” = killer. Used to kill insects, weeds, fungi, etc.
- c) Fertilizers → Help plants grow, don’t kill anything.
- d) Sewage → Waste water from homes → not meant to kill anything.
✔ Correct answer:
b) Pesticides
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Q.12: Which disease is NOT caused due to water pollution directly?
Water pollution usually spreads diseases through dirty water (germs, bacteria, viruses).
- a) Cholera → Caused by drinking contaminated water → yes, from pollution.
- b) Diarrhea → Often from bad water → yes.
- c) Down Syndrome → This is a genetic condition present at birth. Not caused by germs or polluted water. It’s due to an extra chromosome.
- d) Typhoid → Spread through contaminated food/water → yes.
✔ So, the one NOT caused by water pollution is
c) Down Syndrome
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Final Answer:
Q.9: d) Afforestation
Q.10: c) Fertilizers
Q.11: b) Pesticides
Q.12: c) Down Syndrome
Parent Tip: Review the logic above to help your child master the concept of water pollution worksheet high school.
