Study MaterialsNCERT SolutionsNCERT Solutions For Class 7 ScienceNcert Solutions for Class 7 Science Chapter 18 Waste-Water Story

Ncert Solutions for Class 7 Science Chapter 18 Waste-Water Story

Ncert Class 7 Science Chapter 18 Waste-Water Story

The NCERT Solutions Class 7 Science Chapter 18 – Wastewater Story is crucial for the students of 7th standard. The solutions are provided here to assist the students in understanding the Wastewater Story in an easy and interesting way.

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    All the NCERT Solutions are prepared and compiled by subject experts as per the latest CBSE syllabus (2020-2021). It is important for the students to practice the solutions regularly for effective preparation of the examination.

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    1.Fill in the blanks:

    a) Cleaning of water is a process of removing pollutants.

    b) Wastewater released by houses is called sewage.

    c) Dried sludge is used as manure.

    d) Drains get blocked by cooking oil and fats.

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

    A. i) The wastewater containing both liquid and solid wastes produced by human activities, from homes, industries, hospitals, offices and other users etc. is called sewage. It also includes rain water that has run down the street during astrom(or) heavy rain.

    ii) Discharge of untreated sewage into rivers or seas is harmfulbecause :

    a) it pollutes the water present in them.

    b) it contains harmful substances anddisease causing

    c) drinking of such kind of water leads to many health problems.

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

    A. i) Oils and fats get harden and block the sewage pipes.

    ii) In an open drain, fats clog the soil pores and reduce the water filtering efficiency.

    iii) Chemicals like paints, solvents, insecticides, motor oil, medicines may kill microbes that help purify water.

    iv) That is why oils and fats should not be released in the drain.

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

    A. i) In the first step water is passed through bar screens to remove large objects (Rags, Sticks etc.).

    ii) Then water is allowed into grit and sand removal tank.

    iii) In the third step, water is allowed to settle in a large tank to remove sludge and floatable solids (oil, grease etc.).

    iv) Finally aerobic bacteria allowed to grow in the clarified water to remove the unwanted matter.

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

    A. i) Semisolid material that is precipitated by sewage treatment is called sludge. (Or)

    Solids like faeces that settle down during wastewater treatment is called sludge.

    ii) This sludge is removed using a scraper and then transferred to a tank where it is decomposed by anaerobic bacteria to produce biogas.

    6. Untreated human excretais a health hazard. Explain.

    A. i) Untreated human excretacausessoil pollution and water pollution.

    ii) When this polluted or contaminated water is used for drinking, it leads to the occurrence of diseases like cholera, typhoid, polio, hepatitis, etc., and this may even lead to death.

    7. Name two chemicals used to disinfect water.

    A. i) Chlorine

    ii) Ozone

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

    A. i) In wastewater treatment plant, bar screens remove coarse solids and other large materials.

    ii) In this, wastewater is passed through bar screens so that large objects like rags, sticks, cans, plastic packets, napkins, etc., are removed.

    9. Explain the relationship between sanitation and disease.

    A. i) Sanitation and disease are related to each other as lack of sanitation leads to unhygienic conditions and ultimately cause diseases.

    ii) Proper sanitation is necessary to avoid certain kinds of diseases.

    iii) Hence, sanitation and disease are related.

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

    A. i) We can contribute in maintaining sanitation at public places.

    ii) We should not scatter litter anywhere. If there is no dustbin in sight, we should carry the litter home and throw it in the dustbin.

    iii) We must realise our responsibility in maintaining the water sources in a healthy state.

    iv) We should adopt good sanitation practices as our way of life.

    11. Here is a crossword puzzle :

    Across :

    3. Liquid waste products

    4. Solid waste extracted in sewage treatment

    6.A word related to hygiene

    8. Waste matter discharged from human body

    Down :

    1.Used water

    2. A pipe carrying sewage

    5. 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

    A. ii) (b) and (c)

    Introduction to NCERT Solutions Class 7 Science Chapter 18 Wastewater Story

    This chapter specifically deals with the issue of contaminants in the water. Water is an important resource not just for humans but for all the organisms on earth. Therefore, contaminating this natural resource has dire consequences. The main reasons for water pollution are our commercial and industrial activities. All the waste effluents that reach water bodies results in water pollution. In the long run, this can cause many diseases and health hazards for us.

    For instance, in Minamata City, Japan, mercury which runoff from a factory polluted the waters and the poisoning went undetected for decades. It came to notice only when the people saw their newborns had unusual birth defects. It was found that mercury runoff had contaminated the marine ecosystem, resulting in fish species ingesting the mercury. Over a period of time, mercury accumulation in fish species got transferred into human bodies who consumed contaminated fishes. This adversely affected bodily functions and caused a lot of problems for the people and their descendants. Hence, we need to take care of such issues by preventing industrial effluents which pollutes our most precious resource – water.

    Topics Covered in NCERT Solution for Class 7 Science Chapter 18 Wastewater Story:

    Wastewater Story Chapter has 8 subtopics which are listed below.

    1. Water our lifeline
    1. What is sewage
    1. Water freshens up-an eventful journey
    1. Wastewater treatment plant
    1. Better housekeeping practices
    1. Sanitation and diseases
    1. An alternative arrangement for sewage disposal
    1. Sanitation at public places

    Water is a resource that we use for almost all of our activities. Consequently, polluting this resource can adversely affect our health. It is mainly polluted by human activities as a result of commercial or industrial exploits. The waste by-products contain many poisonous chemicals that disrupt the marine ecosystem. Also, human excreta poses a major threat and could potentially be a bio-hazard due to many harmful microbes it carries. These microbes or chemicals could leech into the aquatic environment affecting every life form that comes in contact with it.

    NCERT Solutions Class 7 Wastewater Story guides the students to segregate waste in a way to reduce water pollution. This chapter demonstrates the importance of water in balancing the ecosystem. Students will get to study the meaning of sewage, its treatment and disposal methods. This chapter creates an awareness of sanitation in students, which help them to become responsible citizens.

    Check here to refer the other NCERT Solution for Class 7 Science Chapters.

    Frequently Asked Questions on NCERT Solutions for Class 7 Science Chapter 18

    List the concepts present in the Chapter 19 of NCERT Solutions for Class 7 Science.

    The concepts present in Chapter 18 of NCERT Solutions for Class 7 Science are –[Text Wrapping Break]1. Water our lifeline[Text Wrapping Break]2. What is sewage[Text Wrapping Break]3. Water freshens up-an eventful journey[Text Wrapping Break]4. Wastewater treatment plant[Text Wrapping Break]5. Better housekeeping practices[Text Wrapping Break]6. Sanitation and diseases[Text Wrapping Break]7. An alternative arrangement for sewage disposal[Text Wrapping Break]8. Sanitation at public places

    How to study Chapter 18 of NCERT Solutions for Class 7 Science thoroughly?

    The Chapter 18 of NCERT Solutions for Class 7 Science guides students to segregate waste which leads to reduction in water pollution. The importance of water in balancing the ecosystem is demonstrated clearly in this chapter. By using the solutions, students will get a clear idea about the meaning of sewage, treatment and disposal methods. Students will get an awareness about sanitation which is very important in our day to day life. The solutions are crafted by the experts with utmost care as per the latest CBSE syllabus and guidelines.

    What type of questions can be expected from Chapter 18 of NCERT Solutions for Class 7 Science?

    There are about 12 questions present under this chapter. Students can expect short answer questions and MCQs to appear in the annual exam. Any queries regarding the solutions can be clarified by using the NCERT Solutions from INFINITY LEARN. The solutions are created by the subject experts keeping in mind the understanding abilities of Class 7 students. As Science is one of the important subjects, having a good understanding of basic concepts is necessary to reach their career goals in the same stream.

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