NCERT Grade 7-Wastewater Story-Questions

NCERT Solutions for Class 7 Science

Find 100% accurate solutions for NCERT Class VII Science. All questions have been explained and solved step-by-step, to help you understand thoroughly. Free Download option available!

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Wastewater Story

1.    Fill in the blanks:

(a) Cleaning of water is process of removing ———-.

(b) Wastewater released by houses is called ———.

(c) Dried ——– is used as manure.

(d) Drains get blocked by ——— and —————-.

2.    What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

3.    Why should oils and fats be not released in the drain? Explain.

4.    Describe the steps involved in getting clarified water from wastewater.

5.    What is sludge? Explain how it is treated.

6.    Untreated human excreta is a health hazard. Explain.

7.    Name two chemicals used to disinfect water.

8.    Explain the function of bar screens in a wastewater treatment plant.

9.    Explain the relationship between sanitation and disease.

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

11.   Here is a crossword puzzle: Good luck!


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.

3. Micro-organisms which causes cholera.

7. A chemical to disinfect water.

12.  Study the following statements about ozone:

(a) It is essential for breathing of living organisms.

(b) It is used to disinfect water.

(c) It absorbs ultraviolet rays.

(d) Its proportion in air is about 3%.

Which of these statements are correct?

(i) (a), (b) and (c)

(ii) (b) and (c)

(iii) (a) and (d)

(iv) All four.

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