NCERT Class VII Science Solutions: Chapter 18-Wastewater Story Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 10:

Outline your role as an active citizen in relation to sanitation.


Wastewater treatment plant requires costly infrastructure to build and to be maintained. So, we should be an active citizen and limit the type of waste. Try to follow the following:

  • Open drains be covered and keep our surroundings clean.
  • Should not litter anywhere adopt good sanitation practices e. g. oil and fats should not be thrown in drains.
  • Chemicals like paints, insecticides, motor oil etc. should not be thrown in drain which may kill useful bacteria.
  • Used tealeaves, solid food remains, soft toys, cotton, sanitary towels, etc. should also be thrown in the dustbin.
  • Make people aware and encourage community practices to keep our environment clean.
  • Separate trash as recycled waste and non-recycled.

Question 11:

Here is a crossword puzzle: Good luck!

As Showing in Images is a Crossword Puzzle


3. Liquid waste products

4. Solid waste extracted in sewage treatment

6. A word related to hygiene

8. Waste matter discharged from human body


1. Used water

2. A pipe carrying sewage

5. Micro-organisms which causes cholera

7. A chemical to disinfect water.


As Showing in Images is a Crossword Puzzle

Question 12:

Study the following statements about ozone:

  1. It is essential for breathing of living organisms.
  2. It is used to disinfect water.
  3. It absorbs ultraviolet rays.
  4. Its proportion in air is about 3 % .

Which of these statements are correct?

  1. (a) , (b) and (c)
  2. (b) and (c)
  3. (a) and (d)
  4. All four


ii. (b) and (c)

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