SEBA Class 7 Science Chapter 9 Wastewater Story – Textbook Solutions & MCQ (Part II)
Find Class 7 Science Chapter 9 “Wastewater Story” Solutions for SEBA Assam (English Medium) students. This chapter, from Part II of the Science book, explains how wastewater is generated, its impact on the environment, and the importance of proper sewage treatment. Students will learn about sanitation, wastewater management, sewage treatment plants (STPs), and the need for clean water conservation. Our solutions provide detailed textbook answers, multiple-choice questions (MCQs), and well-explained concepts to help students prepare effectively for their exams.
Class 7 Science
Chapter – 9 (Part II) Ospin Academy
Waste Water Story
EXERCISE
Q. 1. Fill in the blanks:
(a) Cleaning of water is a process of removing _________.
Ans: Pollutants.
(b) Waste water released by houses is called _________.
Ans: Sewage.
(c) Dried ________ is used as manure.
Ans: Sludge.
(d) Drains get blocked by ________ and _______.
Ans: Solid food remains, sanitary towels.
Q. 2. What is sewage? Explains why it is harmful to discharge untreated sewage into rivers or seas.
Ans: Sewage is a liquid containing wastes which is disposed by households, industrial and agricultural activities in water. It is harmful to discharge untreated sewage into rivers or seas because it can pollute the whole source of water. Sewage contains harmful substances and disease causing organisms. It is therefore, dangerous to release untreated sewage in water.
Q. 3. Why should oils and fats be not released in the drain? Explain.
Ans: Oils and fats should not be released in drains because they harden the soil in the pipes and block them. Fats get clogged in holes of the soil in the drain and block it. It does not allow the water to flow.
Q. 4. Describe the steps involved in getting clarified water from wastewater.
Ans: Water is treated physically, chemically and biologically in wastewater treatment plant.
Following steps are involved in the purification of water:
(i) At first stage all the physical impurities like stones, rags, napkins, plastic bags, cans, packets etc., are removed. It is done by passing the water through bar screens.
(ii) Then water is taken to grit and sand removal tank where impurities are removed by sedimentation.
(iii) Solid impurities and feces etc., are collected from the bottom of the water. These solid impurities collected are called sludge. Water is cleared of floatable solids like oil and grease.
(iv) Clarified water is cleared of other impurities by aerator. All disease causing bacteria are removed by chlorination and water is released in various water bodies.
Q. 5. What is sludge? Explain how it is treated?
Ans: Sludge is the collected solid waste from the wastewater during the treatment in water treatment plant. Sludge is decomposed in a separate tank by the anaerobic bacteria. Activated sludge is used as manure.
Q. 6. Untreated human excreta is a health hazard. Explain.
Ans: Untreated excreta can cause a lot of health related problems. It pollutes soil, water and air. The polluted water contains disease causing bacteria, which can spread epidemic like cholera, meningitis etc.
Q. 7. Name two chemicals used to disinfect water.
Ans: Chlorine and ozone are the chemicals used to clean the waste water.
Q. 8. Explain the function of bar screens in a wastewater treatment plant.
Ans: Bar screens clear the wastewater of all the physical impurities. Large waste objects like napkins, plastics, can sticks, rags etc., are removed from the wastewater through the bar screens
Q. 9. Explain the relationship between sanitation and disease.
Ans: Sanitation and disease are related to each other. If sanitation is there no disease will occur, but if the sanitation is not there various types of diseases will occur and spread. So sanitation should be kept to avoid diseases.
Q. 10. Outline your role as an active citizen in relation to sanitation.
Ans: As active citizen we should take care of our personal and environmental sanitation. We should make people around us, aware of the benefits of sanitation. We should help the municipal corporation and gram panchayats to cover all the open drains and remove the unhygienic and disease causing substances thrown in open.
Q. 11. Here is a crossword puzzle: Good! luck
Across
Down
1. Used water.
2. A pipe carrying sewage.
3. Liquid waste products.
4. Solid waste extracted in sewage treatment.
5. Micro-organisms which cause cholera.
6. A word related to hygiene.
7. A chemical to disinfect water.
8. Waste matter discharged from human body.
Ans:
Q. 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 about 3%
Which of these statements are correct?
(i) (a), (b) and (c)
(ii) (b) and (c)
(iii) (a) and (d)
(iv) All four
Ans: (ii)-(b) and (c).
Q1: Why is proper wastewater management important in Class 7 Science?
Proper wastewater management is important to prevent water pollution, conserve clean water, and maintain hygiene in the environment.
Q2: What are the major steps in sewage treatment?
The major steps include screening, sedimentation, biological treatment, and disinfection, ensuring safe disposal of wastewater.
Q3: How does wastewater affect human health and the environment?
Polluted wastewater can cause waterborne diseases, contaminate drinking water, and harm aquatic life.
Q4: Where can I find Class 7 Science Chapter 9 solutions for SEBA Assam?
You can find detailed textbook solutions, MCQs, and explanations for SEBA Assam Class 7 Science Chapter 9 (Part II) on this page.
Q5: Where can I find solutions for all Class 7 Science chapters?
To get solutions for all Class 7 Science chapters, Click Here
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