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Important Questions for CBSE Class 7 Science Chapter 18 - Waste Water Story

  • Class 7 Important Question
  • Chapter 18: Wastewater Story

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CBSE Class 7 Science Chapter-18 Important Questions Wastewater Story Free PDF Download

Free PDF download of Important Questions with solutions for CBSE Class 7 Science Chapter 18 - Wastewater Story prepared by expert Science teachers from latest edition of CBSE(NCERT) books.  Register Online for NCERT Solutions Class 7 Science tuition on Vedantu.com to score more marks in CBSE board examination . Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for the better solutions ,they can download Class 7 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations. 

Study Important Questions for Class 7 Science Chapter 18 - Waste Water Story

Very Short Answer Questions: (1 Marks)

Fill in the Blanks:

1. The United Nations declared the period from 2005-2015 as the International Decade for _______________. 

Ans: Action on the water for life 

2. The suspended impurities in sewage are called _________________.

Ans: Contaminants 

3. The network of small and big pipes that is used for the transport of sewage from the point of production to the point of treatment is called __________________. 

Ans: Sewerage 

4. The sewage that originates from the kitchen is called as _____________. 

Ans: Sullage 

5. Foul waste originates from __________________. 

Ans: Toilets and bathrooms 

6. Wastewater generated by the industries is called as __________________. 

Ans: Trade water 

7. _______________ are used to remove large objects from wastewater. 

Ans: Bar screens 

8. Solid component of sewage is called as _______________. 

Ans: Sludge 

9. Aerobic bacteria that settle in the bottom of the tank after clarification are referred to as ________________. 

Ans: Activated sludge 

10. Septic tanks, chemical toilets and composting pits are examples of ___________________.

Ans: On-site composting

Short Answer Questions: (3 Marks)

1. What is the importance of sewage treatment?

Ans: Sewage is wastewater produced by households and businesses. As a result, it contains material that is hazardous to human health. Water and solid stuff such as faeces make up sewage. If sewage is not treated, the organic stuff in it provides ideal circumstances for the growth of bacteria and other potentially harmful carrier organisms. These organisms have the potential to cause sickness in both humans and animals. Furthermore, sewage has a foul odour that is nauseating and can induce a variety of ailments. Due to a shortage of clean water, this is impossible.

2. How is activated sludge formed?

Ans: The clarified water is then transported to an aeration tank for additional treatment. An aerator is used to introduce air into the cleared water, allowing aerobic bacteria to flourish. These aerobic bacteria then eat any organic substance that remains in the cleared water, such as human waste, food waste, soaps, and so on. These suspended aerobic bacteria settle to the bottom of the tank as activated sludge after many hours.

3. What is the role of grit and sand removal tanks?

Ans: The grit and sand removal tank is a progressively sloped tank where heavier particles such as grit and sand can settle. The pace of water in this tank is substantially slowed. Heavy particles in the wastewater, such as grit and sand, sink to the bottom of the tank when water runs at a near-stagnant rate. After that, the water is transported to the clarifier.

4. How is water clarified in a water clarifier?

Ans: The clarifier is a huge tank with a centre slope. Water is allowed to settle for several hours in this tank. During this time, the sewage's organic solid particles settle at the bottom of the tank. Sludge refers to the solid element of sewage. A scraper is used to scrape and remove the sludge. A skimmer is used to remove floatable materials like oil and grease. Clarified water is the water that is obtained at the end of this operation. The sludge is then moved to a separate tank, where anaerobic bacteria decompose it into biogas and compost. Manure can be utilised as fertiliser and biogas can be used to generate electricity.

5. What are onsite composting methods?

Ans: On-site composting systems treat sewage at the point of production rather than transporting it to a treatment facility. Septic tanks, chemical toilets, compost pits, and other on-site composting technologies include septic tanks, chemical toilets, and compost pits, among others. Such on-site solutions can be used because the volumes of sewage created by tiny units are lower than those generated by a large population. The action of bacteria composts sewage, and cleaned wastewater is subsequently reintroduced into the sewers. The burden on the sewage treatment plants is reduced as a result.

Long Answer Questions: (5 Marks)

1. Suggest better housekeeping practices that can be adopted to reduce waste generation.

Ans: We can utilise a variety of housekeeping methods to reduce sewage and our environmental impact.

1. Cooking fats and oils solidify and clog drains. As a result, they should not be flushed down the toilet.

2. Chemicals can destroy critical sewage-treatment bacteria, therefore they shouldn't be flushed down the toilet.

3. Solid wastes should not be poured down the sink since they clog it. They also obstruct oxygen flow, which has a negative impact on the deterioration process.

4. Do not pollute the environment. If there isn't a garbage bin available, the trash should be transported home and disposed of in the trash can.

2. Poor sanitation leads to diseases. Justify.

Ans: The maintenance of hygiene at the communal level is referred to as sanitation. It entails proper sewage disposal and sustaining communal cleanliness. Sanitation issues imply that hygiene is not being maintained. This happens as a result of incorrect sewage disposal. This allows disease-causing microorganisms and their vectors to reproduce. A rise in the number of pathogenic bacteria increases the chance of developing numerous diseases. Poor sanitation also has an impact on the supply and availability of safe drinking water.  In the lack of safe drinking water, a variety of health issues occur, which can lead to a variety of diseases. In addition, due to a shortage of clean water, recovering from infections would be difficult.

What are the Benefits of Referring to Vedantu’s  Important question for Class 7 Science Chapter 18 - Wastewater Story

Embark on a learning journey with Vedantu’s Important Questions for Class 7 Science Chapter 18 - " Wastewater Story. " These questions serve as your companions, simplifying the intricate tale of wastewater management and emphasizing its importance in our daily lives.

1. Conceptual Focus: Pinpoint key topics within the chapter, ensuring an efficient study session on the critical aspects of the wastewater story for a clearer understanding.

2. Exam Preparedness: Aligned with the vital elements of wastewater management, these questions reduce exam anxiety, fostering confidence and readiness for assessments.

3. Fundamental Reinforcement: Strengthen your understanding of fundamental concepts related to wastewater, laying a solid foundation for comprehending its management principles.

4. Time-Effective Learning: Master effective time management by practicing questions that emphasize essential topics, allowing focused study sessions and optimal preparation for the wastewater story chapter.

Waste Water Story is an integral part of Class 7 Science and plays a crucial role from an examination perspective. The important questions for Class 7 Science, as discussed by NCERT, cover a wide range of topics within the subject. They also provide a concise guide to critical points and details related to the topic.

A solid understanding of each section of Class 7 Science is fundamental as it forms the basis for higher-level studies. However, this section primarily focuses on important questions within the context of Class 7 Science.

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FAQs on Important Questions for CBSE Class 7 Science Chapter 18 - Waste Water Story

1. Why are open drains a concern?

Open drains are a matter of concern due to the reasons given below -

Open drains are a source of agricultural field discharge, sewage discharge, industrial and household kitchen discharge. 

This dirty water gives rise to insects and microbes that cause diseases to human beings. 

If there's a leakage in the drain, then the dirty water can reach the freshwater sources and contaminate them. The contaminated water can cause water-borne infections like Cholera and Amoebiasis in animals and humans.

2. What is a septic tank?

A septic tank is a garbage collecting tank that decomposes human excreta. This tank is made up of concrete, plastic and fibreglass. It consists of an outlet pipe situated at one end and an inlet pipe on the other end. In your house, the toilet seating is attached to the inlet pipe. The inlet pipe transports human excreta into the tank. The solid part of the waste gets collected at the bottom of the tank and the liquid part gets collected at the top of the tank.

3. What is the function of a septic tank?

Septic tanks are used as an alternative to a sewer system that treats human leftovers, solid and liquid wastes in wastewater. Anaerobic bacterias grow onto the waste and break down the solid excreta into simpler forms to reduce the volume of waste to a large extent. These bacterias also decompose liquid waste. Bacterias collect the solid digested part at the bottom of the tank. The extra water goes out into the environment via the outlet pipe and gets soaked by the soil.

4. What do you understand by the term vermicomposting toilet?

A vermicomposting toilet is a form of toilet that decomposes human excreta and other waste products via earthworms. This technique of managing waste has been welcomed by India. It is an excellent method to treat human excreta without using a large quantity of water. A vermicomposting toilet is operated easily without compromising on hygiene. The process of vermicomposting converts human waste into vermi-cakes that are further used to increase the fertility of the soil. 

5. What are the different components of sewage?

Sewage is a combination of different types of impurities like suspended solid waste, inorganic and organic impurities, disease-causing microbes, saprotrophs, nutrients, etc. 

Organic waste includes animal waste, human excreta, urine, oil, kitchen waste, etc. 

Inorganic waste includes phosphates, metals, nitrates, etc. 

The nutrients category includes waste like nitrogen, phosphorus, potassium, etc. 

It contains bacterias that cause Cholera, Dysentery, Typhoid, etc.

Chapterwise Important Questions for CBSE Class 7 Science

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NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

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Table of Contents

Class 7 science, chapter 18 Wastewater Story, explains how wastewater is created, treated, and handled. It teaches students about the importance of saving water and the methods used to clean and reuse wastewater. With clear explanations and fun activities, students learn why it’s important to keep things clean and hygienic for a healthy environment. The NCERT solutions in this chapter aim to encourage young people to be responsible with water and resources.

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NCERT Solutions Class 7 Science Chapter 18 Wastewater Story PDF Download

Download the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story in PDF format to get detailed answers and explanations about wastewater management and treatment. This chapter teaches about the importance of water conservation, the process of treating wastewater, and the need for sanitation for a healthy environment. By downloading the PDF, students can easily access detailed solutions, understand complex concepts, and improve their learning. All NCERT Solutions class 7 are created by subject experts according to the latest CBSE syllabus (2023-24).

NCERT Class 7 Science Chapter 18 Wastewater Story Exercises Solution

Take free test

1. Fill in the blanks:

  • Cleaning of water is a process of removing impurities .
  • Wastewater released by houses is called sewage .
  • Dried sludge is used as manure.
  • Drains get blocked by oils and fats .

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

Sewage is wastewater that contains impurities such as human waste, food scraps, oils, and chemicals. Discharging untreated sewage into rivers or seas is harmful because it pollutes the water, harms aquatic life, spreads diseases, and disrupts ecosystems.

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

Oils and fats should not be released into the drain because they can solidify and block the drainage pipes, leading to clogged and overflowing drains. This can cause sanitation and health problems.

Take free test

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

The steps involved are:

  • Screening: Removing large solids.
  • Primary Treatment: Settling of suspended solids.
  • Secondary Treatment: Biological degradation of dissolved organic matter.
  • Tertiary Treatment: Removing remaining impurities.
  • Disinfection: Killing harmful microorganisms.

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

Sludge is the solid waste separated during the treatment of wastewater. It is treated through processes such as digestion, dewatering, and composting to reduce pathogens and volume, making it safe for disposal or use as manure.

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

Untreated human excreta is a health hazard because it contains harmful pathogens that can cause diseases such as cholera, typhoid, and hepatitis. It can contaminate water sources and the environment, leading to the spread of infections.

Take free test

7. Name two chemicals used to disinfect water.

Chlorine and ozone are two chemicals used to disinfect water.

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

Bar screens are used to remove large solids and debris from wastewater as it enters a treatment plant, preventing damage to equipment and ensuring smooth operation of the treatment process.

9. Explain the relationship between sanitation and disease.

Poor sanitation can lead to the spread of diseases as it provides a breeding ground for pathogens. Proper sanitation practices, such as safe disposal of waste and clean water supply, help prevent the transmission of diseases and promote public health.

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

As an active citizen, you can promote sanitation by practicing proper waste disposal, avoiding littering, participating in cleanliness drives, educating others about hygiene, and supporting policies and initiatives for better sanitation infrastructure.

11. Here is a crossword puzzle: Good luck!

Class 7 Science Chapter 18 Wastewater Story 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

12. Study the following statements about ozone:

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

Which of these statements are correct?

  • (a), (b) and (c)
  • (b) and (c)
  • (a) and (d)

Answer: ii) (b) and (c)

NCERT Solutions for Class Science Other Chapters

  • Chapter 1 Nutrition in Plants
  • Chapter 2 Nutrition in Animals
  • Chapter 3 Fibre to Fabric
  • Chapter 4 Heat
  • Chapter 5 Acids, Bases, and Salts
  • Chapter 6 Physical and Chemical Changes
  • Chapter 7 Weather, Climate, and Adaptations of Animals to Climate
  • Chapter 8 Winds, Storms, and Cyclones
  • Chapter 9 Soil
  • Chapter 10 Respiration in Organisms
  • Chapter 11 Transportation in Animals and Plants
  • Chapter 12 Reproduction in Plants
  • Chapter 13 Motion and Time
  • Chapter 14 Electric Current and Its Effects
  • Chapter 15 Light
  • Chapter 16 Water: A Precious Resource
  • Chapter 17 Forests: Our Lifeline

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story Free PDF

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NCERT Solutions Class 7 Science Chapter 18 Wastewater Story Overview

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.

CBSE Syllabus for Class 7

  • CBSE Class 7 Science Syllabus
  • CBSE Class 7 Maths Syllabus
  • CBSE Class 7 English Syllabus
  • CBSE Class 7 Social Science Syllabus
  • CBSE Class 7 Hindi Syllabus

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

The NCERT class 7 science chapter 18 Wastewater Story covers various topics related to wastewater and its management. Some of the key topics include:

  • Water, Our Lifeline: This section discusses the importance of water in our daily lives and how it is essential for maintaining the ecosystem.
  • What Is Sewage?: This topic explains the concept of sewage, which is the wastewater released by houses and industries.
  • Water Freshens Up-An Eventful Journey: This section describes the journey of water from its source to the wastewater treatment plant.
  • Wastewater Treatment Plant: The chapter discusses the processes involved in treating wastewater to make it safe for reuse or disposal.
  • Better Housekeeping Practices: This topic emphasizes the importance of adopting good housekeeping practices to reduce waste and prevent water pollution.
  • Sanitation and Diseases: The chapter highlights the relationship between sanitation and diseases caused by the presence of pathogens in contaminated water.
  • Alternative Arrangement for Sewage Disposal: This section explores various methods of sewage disposal, such as on-site sewage disposal systems and composting.
  • Sanitation at Public Places: The chapter discusses the role of public sanitation practices in maintaining hygiene and preventing the spread of diseases.

The NCERT solutions for class 7 science Ccapter 18 “Wastewater Story” provide detailed explanations and examples to help students understand these concepts better.

NCERT Solutions for Class 7 All Subject

  • NCERT Solutions for Class 7 Maths
  • NCERT Solutions for Class 7 Science
  • NCERT Solutions for Class 7 Social Science
  • NCERT Solutions for Class 7 English

FAQs on NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

What is wastewater story class 7.

In Class 7 Science Chapter 18, the wastewater story explains how water becomes polluted, the process of wastewater treatment, and the importance of maintaining clean water sources to prevent waterborne diseases and environmental degradation.

What is sludge Class 7 short answer?

In Class 7, sludge refers to the solid waste that settles at the bottom during the wastewater treatment process. It is treated and can be used as manure.

What is wastewater short note?

Wastewater is water that has been used and contaminated by human activities, such as domestic use, industrial processes, and agricultural runoff. It requires treatment before being released back into the environment.

What are the steps involved in getting clarified water from wastewater class 7th science?

The steps include: Screening to remove large objects. Sedimentation to settle solid waste. Filtration to remove smaller particles. Chlorination to kill germs. Aeration to improve water quality.

What are the three sources of wastewater Class 7?

The three sources of wastewater are: Domestic waste from households. Industrial waste from factories. Agricultural runoff from farms.

Where can I find the PDF of NCERT Solutions of Chapter 18 of Class 7 Science?

You can find the PDF of NCERT Solutions for Chapter 18 of Class 7 Science on the Infinity Learn website, where they offer comprehensive and easy-to-understand solutions for students.

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MCQ Questions for Class 7 Science Chapter 18 Wastewater Story with Answers

MCQ Questions for Class 7 Science Chapter 18 Wastewater Story with Answers

We have compiled the NCERT MCQ Questions for Class 7 Science Chapter 18 Wastewater Story with Answers Pdf free download covering the entire syllabus. Practice MCQ Questions for Class 7 Science with Answers on a daily basis and score well in exams. Refer to the Wastewater Story Class 7 MCQs Questions with Answers here along with a detailed explanation.

Wastewater Story Class 7 MCQs Questions with Answers

Choose the correct option.

Question 1. Water that is not fit for use is called (a) clean water (b) wastewater (c) both (a) and (b) (d) none of these

Answer: (b) wastewater

Wastewater Story with Questions and Answers

Question 2. Which of the following is not a source of wastewater? (a) Sewers (b) Homes (c) Industries (d) Hospitals

Answer: (a) Sewers

Wastewater Story with Question and Answer

Question 3. The period of International Decade for action on ‘Water for Life’ is (a) 2000-2010 (b) 2005-2015 (c) 2010-2020 (d) 2003-2013

Answer: (b) 2005-2015

Question 4. The process of removing pollutants in water before it enter a water body is called (a) cleaning of water (b) refining (c) filtering of water (d) none of these

Answer: (a) cleaning of water

Question 5. Which of the following is a part of inorganic impurities of the sewage? (a) Pesticides (b) Urea (c) Phosphates (d) Vegetable waste

Answer: (c) Phosphates

Question 6. Wastewater released by homes, factories, industries and other users is known as (a) polluted water (b) sewage (c) both (a) and (b) (d) none of these

Answer: (b) sewage

Question 7. Suspended impurities contained by sewage are called (a) contaminants (b) sludge (c) grey water (d) none of these

Answer: (a) contaminants

Question 8. A network of big and small pipes under the ground for wastewater management is known as (a) sewage (b) sewerage (c) manhole (d) channel

Answer: (b) sewerage

Question 9. Solid waste extracted during sewage treatment is known as (a) sewage (b) sludge (c) biogas (d) contaminants

Answer: (b) sludge

Question 10. Which portion of WWTP retains large objects like rags, sticks, etc.? (a) Bar screen (b) Sludge (c) Sedimentation tank (d) Sewerage

Answer: (a) Bar screen

Question 11. Name the scraper that removes solids like forced from the wastewater. (a) Skimmer (b) Sludge (c) Tank (d) All of these

Answer: (b) Sludge

Question 12. The equipment that removes floatable particles from wastewater is (a) sludge (b) bar screen (c) skimmer (d) sedimentation tank

Answer: (c) skimmer

Question 13. The tree that helps in wastewater treatment by absorbing water greatly and releasing pure water in environment through transpiration is (a) peepal (b) banyan (c) eucalyptus (d) banana

Answer: (c) eucalyptus

Question 14. Which of the following is a step of wastewater treatment? (a) Aeration (b) Chlorination (c) Filtration (d) All of these

Answer: (d) All of these

Question 15. In a filtration plant, water is filtered using layers of (a) sand and clay (b) clay and fine gravel (c) sand and fine gravel (d) Sand, fine gravel and medium gravel

Answer: (d) Sand, fine gravel and medium gravel

Question 16. Open drain system is a breeding place for which of the following? (a) Flies (b) Mosquitoes (c) Organisms which cause diseases (d) All of these

Question 17. The full form of WWP is (a) World Wide Transport Programme (b) Waste Water Treatment Plant (c) World Worker Talent Programme (d) None of these

Answer: (b) Waste Water Treatment Plant

Question 18. Sewage is mainly a (a) liquid waste (b) solid waste (c) gaseous waste (d) Mixture of solid and gas

Answer: (a) liquid waste

Question 19. Which of the following is not a water-borne disease? (a) Cholera (b) Tuberculosis (c) Typhoid (d) Dysentery

Answer: (b) Tuberculosis

Question 20. Which of the following is the characteristic quality of wastewater? (a) Dirty look (b) Foul smell (c) Bad taste (d) All the above

Answer: (d) All the above

Question 21. Which of the following is a part of inorganic impurities of the sewage? (a) Excreta (b) Garbage (c) Phosphate (d) Vegetable waste

Answer: (c) Phosphate

Question 22. Which of the following is the step of wastewater treatment? (a) Chlorination (b) Aeration (c) Filtration (d) All of the above

Answer: (d) All of the above

Question 23. The aerobic bacteria can be grown in clarified water by (a) filtration (b) sewage (c) aeration (d) sedimentation

Answer: (c) aeration

Question 24. Chlorine is used in municipal water treatment plant to (a) change the taste of water (b) prevent evaporation (c) kill the harmful microorganisms (d) prevent sedimentation

Answer: (c) kill the harmful microorganisms

Question 25. Which of the following is not an inorganic impurity present in sewage? (a) Nitrate (b) Phosphorus (c) Urea (d) Metal salt

Answer: (c) Urea

Fill in the Blanks

Question 1. Wastewater should be cleaned up by removing ……………..

Answer: pollutants

Question 2. Some factors responsible for the increasing scarcity of freshwater are ……………..

Answer: population growth; pollution; mismanagement

Question 3. The General Assembly of the …………….. proclaimed the period 2005-2015 as the International Decade for action on ‘Water for Life’.

Answer: United Nation

Question 4. Sewage is a …………….. waste.

Answer: liquid

Question 5. Sewage contains some organic impurities like oil, …………….. , …………….. and ……………..

Answer: urea; human faeces; animal waste

Question 6. Air is pumped into the clarified water to help …………….. bacteria to grow.

Answer: aerobic

Question 7. The full form of WWTP is ……………..

Answer: wastewater treatment plant

Question 8. Sewage causes …………….. and …………….. pollution.

Answer: water, soil

Question 9. Activated sludge mainly contains water and ……………..

Answer: microbes

Question 10. Dried sludge is used as ……………..

Answer: manures

Question 11. Water is the basic constituent of all ………………….

Answer: living beings

Question 12. Sewage is a liquid waste which causes …………………. and …………………. pollution.

Question 13. Untreated human excreta is a …………………. hazard.

Answer: health

Question 14. During the aeration of clarified water, …………………. bacteria can be grown.

Question 15. Cleaning of water is a process of removing ………………….

Question 16. Wastewater released by household is called ………………….

Answer: sewage

Question 17. Vermi-composting toilets use …………………. to treat human waste.

Answer: earthworms

True or False

Question 1. Wastewater is suitable for drinking purpose.

Answer: False

Question 2. Wastewater can be revised.

Answer: True

Question 3. Clean water is available for every person.

Question 4. Pollution is one of the factors of the increasing scarcity of freshwater.

Question 5. World Water Day is celebrated on 22 March every year.

Question 6. Cleaning of water is also known as sewage treatment.

Question 7. Sewage is wastewater.

Question 8. The water that washes off the road and rooftop is fit for drinking.

Question 9. Sewage contains many harmful substances which are known as sewerage.

Question 10. From wastewater, skimmer remove the floating particles like oil and grease.

Question 11. Where underground sewerage systems and refuse disposal systems are not available, the high cost on-site sanitation system can be adopted.

Question 12. The activated sludge is about 94% water.

Question 13. Dried sludge is used as manure.

Question 14. After cleaning the sewage, it is directly used by humans.

Question 15. Nutrient-rich sewage water supports the growth of algae.

Question 16. Clean water is a basic need of human beings.

Question 17. Used water is clean water.

Question 18. Treatment plants reduce pollutants in wastewater to a level where nature can take care of it.

Question 19. Open drain system is a breeding place for flies, mosquitoes and organisms which cause diseases.

Question 20. People should defecate in the open.

Question 21. Biogas is released by anaerobic bacterial.

Question 22. Sanitation is not important for a community.

Match the following

Column I Column II
1. Organic impurities (a) Sewage treatment
2. WWTP (b) Required oxygen
3. Inorganic impurities (c) Removal of large objects
4. Aerobic bacteria (d) Decomposes sludge
5. Vermi-processing toilet (e) Nitrates, phosphates
6. Bar screens (f) Disinfect water
7. Chlorine and ozone (g) Herbicides and pesticides
8. Anaerobic bacteria (h) Earthworms
9. Last stage of WWTP (i) Chemical treatment
10. First stage of WWTP (j) Physical treatment
Column I Column II
1. Organic impurities (g) Herbicides and pesticides
2. WWTP (a) Sewage treatment
3. Inorganic impurities (e) Nitrates, phosphates
4. Aerobic bacteria (b) Required oxygen
5. Vermi-processing toilet (h) Earthworms
6. Bar screens (c) Removal of large objects
7. Chlorine and ozone (f) Disinfect water
8. Anaerobic bacteria (d) Decomposes sludge
9. Last stage of WWTP (i) Chemical treatment
10. First stage of WWTP (j) Physical treatment
Column A Column B
1. Bacteria (a) Pesticides and herbicides
2. Inorganic impurities (b) Transport system that carries sewage
3. Sewerage (c) Cholera and typhoid
4. Earthworm (d) Nitrates and phosphates
5. Organic impurities (e) Used in verminprocessing toilets
Column A Column B
1. Bacteria (c) Cholera and typhoid
2. Inorganic impurities (d) Nitrates and phosphates
3. Sewerage (b) Transport system that carries sewage
4. Earthworm (e) Used in verminprocessing toilets
5. Organic impurities (a) Pesticides and herbicides

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NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF Download

By referring to the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story, students can learn to approach questions in different ways. These different approaches can be implemented while attempting Chapter 18 Wastewater Story questions from the final exams; accordingly, students can score well. By solving more questions from Chapter 18 Wastewater Story, students can easily improve the speed of attempting questions which can be helpful during exams or tests. 

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF

Solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF can assist students to grasp the important concepts. Students can solve Chapter 18 Wastewater Story questions from their comfort zone through the Selfstudys website as it is available in the portable document format. After solving questions of Chapter 18 Wastewater Story, students can also refer to a website to solve doubts as the answers are already available on the website. 

Where can Students Find the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story? 

Students can find the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story without any difficulty, steps are discussed below: 

  • Visit the Selfstudys website. 

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story, NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF, NCERT Class 7 Science Solutions Chapter 18 Wastewater Story, NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story Revision, NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story Theory

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  • A new page will appear, now Class 7 from the list of classes. 
  • Select Science from the list of subjects.
  • Now select Chapter 18 Wastewater Story from the list of chapters. 

Features of NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

The features of NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story are considered to important part which students need to know; some of the features are discussed below: 

  • Objective Questions are Included: In this type of questions of Chapter 18 Wastewater Story students need to select the accurate answers according to their knowledge. These questions are included in the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story revision.
  • All Exercises are Covered: In the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory, all the exercises are covered so that students can find different ways to attempt different questions. 
  • Diagrams are Included: Diagrams are considered to be graphical representation of the Chapter 18 Wastewater Story concepts; these diagrams are included in the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF. 
  • Available in the PDF: Students can start solving Chapter 18 Wastewater Story questions from NCERT Class 7 Science Solutions as it is already available in the portable document format. 
  • All Topics are Covered: Before solving questions of Chapter 18 Wastewater Story from the NCERT Class 7 Science Solutions, students need to complete all the topics as it is covered through the questions. 
  • Free Accessibility: The Chapter 18 Wastewater Story questions of Class 7 Science NCERT Solutions have free accessibility, that is students don’t need to pay any kind of amount. 

Exploring the Benefits of NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

Students need to explore the benefits of NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story so that they can score well; some of the benefits are: 

  • Helps in Tackling Difficult Questions: The NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story revision helps students in tackling difficult problems by providing different approaches. 
  • Get to Know About the Drawbacks: By solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory, students can get to know about the drawbacks and accordingly they can eliminate them. 
  • Provides Step Wise Solutions: The questions in the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF are explained in step wise manner so that students can understand each and every step without any difficulty. 
  • Helps to Solve Doubts: By referring to the Chapter 18 Wastewater Story questions and answers in the NCERT Class 7 Science Solutions, students can easily solve the doubts and confusions; and can improve accordingly. 
  • Helps to Boost Confidence: Students who solve Chapter 18 Wastewater Story questions from the NCERT Class 7 Science Solutions can easily boost their confidence level. 
  • Boosts Accuracy: Answers of Chapter 18 Wastewater Story questions from the NCERT Solutions for Class 7 Science are accurate; so by going through it, students can automatically improve their accuracy level. 

Are NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story Right for Students?

Yes, the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story is right for students for various reasons, which are discussed below: 

  • Can Understand the Concepts: The NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story revision is right for students as it helps students to understand the concepts and topics in a proper manner. 
  • Best Tool for Revision: Students can prefer NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory as it acts as revision tool. The reason for it acting as a revision tool is that it includes all topics and concepts of Chapter 18 Wastewater Story. 
  • Can be Used as Self Study Tool: The NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF is right for students as it can be used as a self study tool. By self assessment, students can get an idea about their strengths and weaknesses of Chapter 18 Wastewater Story; accordingly they can improve it. 
  • Helps to Score Well: It is advisable for students to solve Chapter 18 Wastewater Story questions from the NCERT Solutions for Class 7 Science so that they can easily score well in the final exams. 
  • Includes Examples: The NCERT Solutions for Class 7 Science is right for students to complete Chapter 18 Wastewater Story as it includes examples with relevance to real life so that they can understand the questions properly. 
  • Provides Updated Syllabus: Students can prefer the NCERT Solutions of Class 7 Science to solve questions from Chapter 18 Wastewater Story as it is arranged according to the latest and updated syllabus. 

Strategies to Solve Questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

Strategies are considered to be action to achieve a goal; the same is followed while solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story; those strategies are discussed below: 

  • Read the Question Carefully: Students should read the question from NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story revision very carefully so that they can analyse what is being asked. 
  • Refer to the Textbook: To solve questions from NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory in an effective way, they need to refer to the textbook. By referring to the Class 7 Science textbook, students can understand the concepts of Chapter 18 Wastewater Story which can be implemented while solving questions. 
  • Use Diagrams and Illustrations: While solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory, students need to give diagrams and illustrations wherever there is a need. By giving diagrams and illustrations, students can score well in Chapter 18 Wastewater Story questions. 
  • Develop a Plan to Solve: Students need to develop their own plan to solve questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story PDF. By developing their own plan, students can save their time and probably don’t waste time on one single question. 
  • First Solve Easy Questions: It is advisable for students to first identify the easy questions of Chapter 18 Wastewater Story from NCERT Class 7 Science Solutions rather than solving the complex; this can make the solving process much easier. 
  • Make a Concept Map: In the process of learning Chapter 18 Wastewater Story of Class 7 Science, students should make their own concept map and need to start with the key topics. By making concept maps, students can solve Chapter 18 Wastewater Story questions from the Class 7 Science. 

How to Rectify Mistakes After Solving Questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story? 

The rectification of mistakes after solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story is the most essential part in the learning process; tips to rectify the mistakes are discussed below: 

  • Identify the Mistakes: Students need to identify the mistakes of questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story revision so that they can easily look for the errors. 
  • Understand the Cause of Mistakes: After identification of mistakes, students should understand the cause of mistakes of Chapter 18 Wastewater Story Science questions from NCERT Class 7 Science Solutions ; reasons can be due to lack of understanding concepts, careless mistakes, spelling mistakes, etc. 
  • Get Rid of Any Distractions: While solving questions from the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story theory, they need to get rid of distractions so that they can minimise and rectify the mistakes easily. 
  • Form a Study Group: To rectify the mistakes after solving Chapter 18 Wastewater Story questions from the NCERT Class 7 Science Solutions, students need to make study groups. Through making study groups, students can set a learning goal to practise Science Chapter 18 Wastewater Story questions. 
  • Practise Similar Questions: In the process of rectification of mistakes after solving Chapter 18 Wastewater Story questions from the Class 7 Science NCERT Solutions, students need to practise similar sets of questions. 
  • Seek Help: If in case, students are struggling to rectify the mistakes after solving Chapter 18 Wastewater Story questions from the Class 7 Science NCERT Solutions, they can seek help from the concerned teachers. 

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NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

NCERT Solutions for Class 7 Science Chapter 18 have been provided in the article below for the students of CBSE Class 7 Science. Those interested can check the detailed solutions on this page

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January 8, 2024

class 7 science chapter 18 case study questions

Table of Contents

NCERT Solutions for Class 7 Science Chapter 18

NCERT Solutions for Class 7 Science Chapter 18: NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story is essential for 7th-grade students. These solutions aim to help students understand the Wastewater Story easily and quickly. All the solutions are created by subject experts following the latest CBSE syllabus (2023-2024). Regular practice of these solutions is crucial for effective exam preparation.

NCERT Solutions for Class 7 Science Chapter 18 highlight the significance of water in everyone’s life. The chapter explains how clean water can turn into dirty water and suggests measures to reuse and recycle wastewater. Each section in NCERT Science Class 7 Science Chapter 18 helps students understand important concepts.

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NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story Overview

NCERT Solutions for Class 7 Science Chapter 18 focus on issues related to contaminants in the natural resource of water and their serious consequences. It discusses activities causing pollution and their negative impact on health. The chapter also addresses the conversion of wastewater from human activities leading to soil and water pollution. It emphasises the use of a Wastewater Treatment Plant to reduce pollutants in nature and the adoption of low-cost on-site Sanitation Systems when sewage systems are unavailable. 

However, the by-products of the Wastewater Treatment Plant include Biogas and Sludges. The chapter also mentions the negative consequences of an Open Drainage System, which harbours organisms, flies, and mosquitoes causing diseases. Therefore, the chapter stresses the importance of water, proper waste disposal, the use of Wastewater Treatment Plants, sanitation, and the consequences of open defecation.

NCERT Solution of Class 7 Science Chapter 18 acts as a guide for students, listing important measures to reduce water pollution and contamination. The chapter emphasises the importance of maintaining water balance in the ecosystem and raises awareness about sanitation among students.

NCERT Solutions for Class 7 Science Chapter 18 serves as a reliable reference, providing students with a concise yet comprehensive grasp of the Wastewater Story. These solutions cover key concepts and topics, making them an invaluable resource for students preparing for annual exams or intermediate tests. Accessing the NCERT Science Book Class 7 Science Chapter 18 aids in gaining a thorough understanding of essential concepts. Students can enhance their preparation by accessing and utilising these solutions

Fill in the blanks:

1. Cleaning of water is the process of removing ________. 

Ans: Cleaning of water is the process of removing contaminants .

2. Wastewater released by houses is called ________. 

Ans: Wastewater released by houses is called sewage .

3. Dried ________ is used as manure.

Ans: Dried dung is used as manure.

4. Drains get blocked by ________ and ________.

Ans: Drains get blocked by plastic and sludge .

Q1. What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas. 

Ans: Sewage is a kind of used water or wastewater that has been emitted by houses, industries, hospitals, offices, and other users. It also features subsurface storage for rainfall. It may contain dangerous chemicals and organisms that can endanger human life. Algae can quickly develop when given various nutrients, resulting in a decreased amount of dissolved oxygen in the water. This is why sewage should not be discharged into seas and rivers.

Q2. Why should oils and fats be not released in the drain? Explain. 

Ans: Oil and fats should not be poured down the drain since they are not dissolved in water and float on top of it. It can clog drains and, if released into bodies of water, can harm aquatic life.

Q3. Describe the steps involved in getting clarified water from wastewater. 

Ans: Wastewater treatment has physical, chemical, and biological processes.

  • Waste water is filtered using bar screens to eliminate large materials such as rags, twigs, cans, plastic packets, napkins, and so on.
  • Water is routed through a grit and sand removal tank, allowing sand, grit, and pebbles to settle.
  • The water is then allowed to settle in a big settling tank, where solid faeces known as sludge is removed using a scarper.
  • Air is poured into the clarified water to assist aerobic bacteria in growing and consuming wastes.
  • Water of this kind is dumped into rivers or ponds.

class 7 science chapter 18 case study questions

Q4. What is sludge? Explain how it is treated.

Ans: Sludge is a solid waste material that settles in secondary water treatment. Generally, it is scraped out from the bottom. The clarified water is then discharged. Sludge is stored in a separate tank and treated with anaerobic bacteria, which creates biomass that can be used as bio manure.

Q5. Untreated human excreta is a health hazard. Explain.

Ans: Millions of bacteria live in the human stomach and expel with the faeces. If human excreta is dumped directly into the soil or water, it can pollute both the water and the soil. Under favourable conditions, the bacteria divide and multiply, and when the water reaches the earth table, it might affect a bigger population that consumes it. It can induce water-borne diseases such as typhoid and cholera.

Q6. Name two chemicals used to disinfect water.

Ans: Water disinfection involves removing or deactivating pathogenic bacteria, as well as killing them. Microorganisms are rendered inactive, putting an end to their development and reproduction. If germs are not removed from drinking water, humans will develop unwell from drinking water. Chlorine and ozone are the two chemicals used in water disinfection.

Q7. Explain the function of bar screens in a wastewater treatment plant. 

Ans: When waste water is pumped through bar screens, it serves as a large screen. In the first step of cleaning water, large materials such as rags, twigs, cans, plastics, and napkins are removed.

Q8. Explain the relationship between sanitation and disease. 

Ans: Sanitation is a public health issue. Sanitation includes the prevention of disease, the provision of safe drinking water, and the proper disposal of garbage. Diseases are spread when cleanliness standards are not met. Dirty water serves as a breeding ground for mosquitoes that transmit diseases. Improper sewage disposal can result in water-borne sickness. As a result, sanitation is the utmost pathogen rescue and can result in a disease-free environment.

Q9. Outline your role as an active citizen in relation to sanitation. 

Ans: All humans have a responsibility to play in keeping our environment clean as engaged and knowledgeable citizens. We can begin from home. Adopting excellent sanitation techniques should be a way of life for all of us. Our energy, ideas, and excitement can have an impact on others. And encourage people to maintain a healthy living environment for the benefit of society.

Q10. Here is a crossword puzzle: Good luck! 

1. Liquid waste products.

2. Solid waste extracted in sewage treatment.

3. A word related to hygiene

4. Waste matter discharged from the human body. 

1. Used water.

2. A pipe carrying sewage.

3. Micro-organisms which cause cholera.

4. A chemical to disinfect water.

Ans: Across: 1. Liquid waste product- Sewage 2. Solid waste extracted in sewage treatment- Sludge 3. A word related to hygiene- Sanitation 4. Waste matter discharged from human body- Excreta

Down:                                                                                                                                    

1. Used water- wastewater

2. A pipe carrying sewage- Sewer

3. Microorganisms which causes cholera- Bacteria  

4. A chemical to disinfect water- Ozone

Study the following statements about ozone:

1. It is essential for the breathing of living organisms.

2. It is used to disinfect water.

3. It absorbs ultraviolet rays.

4. Its proportion in the air is about 3%.

Which of these statements are correct? 

  • a., b. and c.

iii. a. and d.

1. All four

Explanation: Ozone, often known as trioxygen, is an inorganic molecule having the formula O3O3. It’s a pale blue gas with a pronounced unpleasant odour. Oxygen is required for living beings to breathe. As a result, statement a. is incorrect

Ozone is a powerful oxidant, even more potent than chlorine. Ozone is used in water to disinfect, deodorise, decolorize, and degrade organic compounds. As a result, statement b. is correct.

The ozone layer, also known as the ozone shield, is an area of the earth’s stratosphere that absorbs the majority of the sun’s UV radiation. As a result, statement c. is correct.

The concentration of ozone in the atmosphere is 0.000004%0.000004%. As a result statement d. is incorrect.

Therefore, the correct answer is (ii).

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NCERT Solutions for Class 7 Science Chapter 18 WasteWater Story Topics Covered

The Chapter covers several key points, including:

  • Wastewater is water that’s been contaminated from various sources and needs proper treatment before use. All discharges from places like homes, hospitals, businesses, and industries are known as effluent.
  • Wastewater includes agricultural, horticultural, stormwater, urban runoff, and aquaculture effluent.
  • Effluent is the sludge or sewage released into water bodies, either directly or after treatment.
  • Contamination occurs when one substance, like bacteria, makes another substance impure, such as contaminating food or water.
  • Sewage is liquid waste that pollutes water and soil, containing suspended materials, organic and inorganic pollutants, nutrients, saprophytic and disease-causing bacteria, and other microbes.
  • Wastewater treatment plants remove contaminants to a level sustainable for the environment.
  • Low-cost on-site sanitation is an alternative method for waste treatment where underground sewerage and trash disposal systems aren’t available.
  • Sludge and biogas are by-products of wastewater treatment.
  • Open drains shouldn’t be used for defecation as they become breeding grounds for flies, mosquitoes, and disease-causing organisms.
  • Proper disposal of excreta is crucial, especially in rural and developing areas, using low-cost methods.

Benefits of NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

NCERT solutions for Class 7 Science, Chapter 18, or any other chapter, offer several advantages:

1. Aligned with Curriculum: NCERT solutions are designed to be in sync with the CBSE curriculum. They cover the topics and concepts outlined in the official curriculum, ensuring that students are well-prepared for exams.

2. Accuracy and Credibility: NCERT is a reputable organisation, and its solutions are well-researched and accurate. Students can rely on these solutions for correct information and answers.

3. Clear Explanation: The solutions provided in NCERT textbooks are written in a clear and concise manner. This helps students understand complex concepts more easily, making the learning process more effective.

4. Structured Approach: The solutions are presented in a structured format, helping students organise their thoughts and understand the logical flow of concepts. This can enhance their problem-solving skills.

5. Exam Preparation: NCERT solutions are an excellent resource for exam preparation. They provide a comprehensive review of the topics covered in each chapter, helping students revise and practice before exams.

6. Additional Practice Material: NCERT solutions often include additional exercises and questions for practice. This allows students to reinforce their understanding of the concepts and improve their problem-solving skills.

7. Language Clarity: The language used in NCERT solutions is simple and easy to understand. This is particularly beneficial for students who may find certain scientific terms or concepts challenging.

8. Encourages Self-Study: NCERT solutions are designed to be student-friendly, encouraging self-study. Students can use these solutions independently, enhancing their ability to learn and apply concepts without constant guidance.

9. Conceptual Understanding: Instead of rote memorization, NCERT solutions emphasise conceptual understanding. This approach fosters a deeper comprehension of scientific principles, which is crucial for long-term retention and application.

10. Widely Accepted: NCERT textbooks and solutions are widely accepted and used across schools in India. This ensures uniformity in the educational system and allows students to have a consistent learning experience.

NCERT Solutions for Class 7 Science Chapter 18 FAQs

Sludge is a semi-solid residue that forms during the wastewater treatment process. Its treatment involves various steps like sedimentation, digestion, and dewatering to minimise volume and mitigate environmental impact.

Inadequate sanitation facilitates disease transmission by allowing pathogens to spread through contaminated water and poor hygiene practices.

There are a total of 12 questions addressed in NCERT Solutions for Class 7 Science Chapter 18 - Wastewater Story.

NCERT Solutions for Class 7 Science Chapter 18 - Wastewater Story contains 4-8 questions with detailed solutions exceeding 180 words.

Wastewater, as portrayed in Chapter 18 of Class 7 Science, is water that has been utilised and contaminated with impurities, necessitating proper treatment before safe disposal.

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Important Questions Class 7 Science Chapter 18

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Important Questions Class 7 Science Chapter 18 – Wastewater Story

The eighteenth chapter of the Class 7 Science curriculum is about Wastewater Story. The chapter covers topics of wastewater, sewage, wastewater treatment plant, sanitation and waterborne disease management, an alternative arrangement for sewage disposal management, etc.

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To score well in Science, students must read through all the chapters and revise by practising a lot of questions. Extramarks understand the importance of regularly solving questions. To help students provide a comprehensive set of questions, our faculty experts have collated questions of varying degrees of difficulty levels from various sources such as NCERT textbook and exemplar, other reference books, past years’ question papers, etc. Our experienced faculty have prepared step-by-step solutions with detailed explanation of all concepts covered in Chapter 18. Students can refer to our Important Questions in Class 7 Science Chapter 18 to start practising. 

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Important Questions Class 7 Science Chapter 18 – With Solutions

Given below are a list of a few questions along with their answers from our question bank of Chapter 18 Class 7 Science Important Questions.

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Question 1. What are onsite composting methods?

Answer 1. Onsite composting systems treat wastewater at the point of production rather than transporting it to a treatment facility. Septic tanks, chemical toilets, composting pits, and other onsite composting technologies include septic tanks, chemical toilets, and compost pits, among others. Such onsite solutions can be used because the quantities of sewage created by tiny units are lower than those generated by a large population. The bacterial action composts sewage, and cleaned wastewater is reintroduced into the sewers. The load on the sewage treatment plants is reduced as a result.

Question 2. What is the importance of sewage treatment?

Answer 2. Households and industries produce sewage. As a result, it contains a substance that is dangerous to health. Water and solid stuff such as faecal matter make up sewage. If sewage is not treated, the organic material in it provides ideal conditions for the growth of bacteria and other very harmful carrier organisms. These organisms can cause diseases in both humans and animals. Further, sewage has a foul odour that is nauseating and can induce a variety of illnesses. Due to the scarcity of clean water, this is impossible.

Question 3. Explain the steps involved in getting clarified water from wastewater.

Answer 3. Use an aerator from an aquarium to bubble air through the sample in the glass bottle. Allow a few hours for aeration; leave the aerator attached for one day. You can use a mechanical stirrer or a mixer if the aerator is unavailable. This reduces the foul smell of wastewater.

Then, the water is filtered through the sand, fine gravel and medium gravel layers. Filtration makes the wastewater clean from various types of pollutants. The water is filtered continuously until it becomes clear.

Water is disinfected by using a chlorine tablet.

Question 4. Name two chemicals used to disinfect water

Answer 4. Chlorine and Ozone chemicals are used to disinfect water.

Question 5. Write the function of bar screens in a wastewater treatment plant. 

Answer 5. The bar screen removes large objects like rags, sticks, cans, plastic packets and napkins.

Question 6. Outline your role as an active citizen concerning sanitation.

Answer 6. Each citizen has a role in maintaining proper sanitization. Following are some of the ways through which this can be done.

  • i) Ensure that our surroundings are kept clean.
  • ii) The sewage system in the house should be managed appropriately

iii) Report to the concerned authority immediately in case of leakages in sewage pipes.

Question 7. Define sewage and explain why it is harmful to discharge untreated wastewater into rivers or seas.

Answer 7. Wastewater discharged by houses is called sewage . Untreated sewage should not be discharged directly into the sea because sewage consists of pollutants and harmful microorganisms which will contaminate water, causing disease or sickness among people who consume it. .

Question 8. Which is/are the products of wastewater treatment?

(c) Both biogas and sludge

(d) Aerator

Answer 8. The answer is option (c) Both biogas and sludge.

Explanation: Water can settle in a large tank sloped towards the middle during wastewater treatment. Solids like faeces are set at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the buoyant solids like oil and grease. Water that is so clean is called clarified water. The sludge is transferred to another tank where anaerobic bacteria decompose it. The biogas formed in the process can be used as fuel or to produce electricity.

Question 9. How are open drains harmful to our health?

Answer 9. The open draining system causes problems with the foul smell. An open drainage system is the breeding source for mosquitos and flies. The available drainage system also helps the growth of disease-causing organisms. Hence drains are harmful to human health.

Question 10. What are the various steps of cleaning wastewater in a wastewater treatment plant?

Answer 10. Wastewater treatment involves physical, chemical, and biological processes which remove physical, chemical and biological matter contaminating the wastewater.

  • Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastics and napkins are removed.
  • Water then goes to a stone and sand removal tank. The speed of the incoming wastewater is reduced to allow sand, stones and pebbles to settle down.
  • The water was then settled in a large tank tilted towards the middle. Solids like faeces are set at the bottom and are removed with a scraper. This is called sludge. A skimmer removes the floatable materials like oil and grease. Water so cleared is called clarified water. The sludge is moved to a separate tank where anaerobic bacteria decompose it. The biogas produced in this process can be used as fuel or to generate electricity.
  • Air is pumped into the clarified water that helps aerobic bacteria to grow. These bacteria consume human waste, food waste, soaps and other unwanted matter remaining in clarified water. 

After a few hours, the floating microbes were set at the bottom of the tank as activated sludge. The water is then taken from the top. This activated sludge is approx 97% water. Sand drying beds or machines remove the water. Dried sludge is used as manure, and organic matter and nutrients return to the soil. The treated water has a very low organic material and floating matter. It is discharged into a sea, a river or the ground. Nature then cleans it up. Sometimes it is necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

Question 11. The terms sewage, sewers and sewerage are interlinked with each other. Can you explain how?

Answer 11. The terms ‘sewage, ‘sewers,’ and ‘sewerage are interlinked with each other because sewage is a mixture of wastewater coming out of homes and other places. Sewers carry sewage, and sewerage is a network of sewage-carrying pipes.

Benefits of Solving Important Questions Class 7 Science Chapter 18

Science is a subject that requires constant reading and revising of different topics and concepts covered across all the chapters. Class 7 students are advised to go through Extramarks Important Questions Class 7 Science Chapter 18. The solutions for all the questions are prepared by Science subject experts and will help students thoroughly understand the concepts that are covered in each question. 

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Q.1 Select the correct order of steps taken in WWTP.

(a). bar screens, scrapper, grit and sand removal tank, aerator, ozone

(b). bar screens, grit and sand removal tank, scrapper, aerator, ozone

(c). bar screens, grit and sand removal tank, scrapper, ozone, aerator

(d). bar screens, grit and sand removal tank, aerator, scrapper, ozone

The wastewater is first passed through bar screens which remove big objects. The wastewater is then sent to a grit and sand removal tank. The sludge is then separated from the water with the help of a scrapper, then it is moved to an aerator that pumps air into it. Harmful chemicals are removed by using disinfectants such as the ozone.

Q.2 Which factor is not responsible for increasing the scarcity of fresh water?

(a).Pollution

(b). Population growth

(c). Mismanagement

(d). Chlorination

Chlorination is used for making water bacteria free.

Q.3 After frying pakoras, some oil with suspended solid impurities was left in the frying pan. Answer the following questions based on the given situation: a) Can the leftovers be released into the drain? Explain your answer. b) Suggest a suitable technique by which the leftovers can be managed.

a) No, the leftover oil cannot be released into the drain because the solid impurities and the oil will clog the drain and will not allow free flow of oxygen. This will hamper the degradation process. b) The impure oil must be filtered off and the solid impurities must be thrown into the dustbin. The remaining oil must be stored separately in a container and be reused later.

Q.4 Answer the following questions. 1. What is a manhole? 2. Where are manholes located? 3. What is the function of manholes? 4. Define sewers. 5. Which nutrients are found in sewage?

(a) A large, covered hole on the ground, pavement, or road above the underground sewer system is known as a manhole. (b) Manholes are positioned every 50 to 60 metres in the sewer, at the intersection of two or more sewers and at spots where the direction of the sewage changes. (c) The sanitary workers can enter the sewer systems through the manholes to clean or repair any leaks or blockages. (d) The underground pipes that carry wastewater separately are known as sewers. (e) Nitrogen and phosphorus are found in sewage.

Q.5 Why is defecation in open considered as a big problem?

A large fraction of people defecates in the open, on dry river boards, railway tracks and many times directly in water. Due to this, groundwater and surface water gets polluted. This polluted water gives rise to many diseases. Hence, defecation in open is considered as a big problem.

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Faqs (frequently asked questions), 1. where can a student easily find important questions class 7 chapter 18.

Students can easily register with Extramarks and gain access to Important Questions Class 7 Science Chapter 18. These important questions cover the entire chapter. Made by subject experts, these questions and their solutions are entirely authentic and exclusive. And help students achieve better grades in their examinations.

2. What books are recommended to learn about Chapter 18 Wastewater story and other chapters of Class 7 Science?

The Central Board of Secondary Education (CBSE) recommends NCERT Class 7 Science textbook and exemplar. The textbook has in-depth coverage of each topic with narratives and real-life examples to make learning interesting and engaging for students. It also comes with a lot of exercises and questions to help students check their understanding of the concepts.  The book consists of 18 chapters that discuss important topics from general science. 

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3. What are the best practices to understand the concepts of the given topics from Class 7 Science?

Students should start their studies by referring to the NCERT textbooks. Along with the textbook, it’s a good idea to refer to reliable study resources from Extramarks. Students can refer to our NCERT solutions which include comprehensive chapter notes covering all aspects of the chapter. Regularly solving questions from our Important Questions Class 7 Science Chapter 18 will further help students to revise the chapter and also understand their weak areas. These solutions will assist students in developing a clear understanding of the key concepts in an easy-to-understand language and help them to get excellent scores.

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  • NCERT Exemplar
  • NCERT Exemplar Class 7
  • Class 7 Science
  • Chapter 18 Wastewater Story

NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story

NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story are given here for students to improve their understanding of the concepts provided in the NCERT Class 7 Science textbook.

The NCERT Exemplar for Class 7 Science helps in enhancing the problem-solving ability among students by practising problems provided in the NCERT Exemplar book. It offers explanations for multiple-choice questions and true or false questions, along with the answers to match the following and detailed descriptions for long answer questions.

This exemplar solution has answers to 10 multiple choice questions, 3 very short answer questions, 9 short answer questions and 5 long answer questions that are provided in the NCERT Exemplar book. Referring to this exemplar solution will boost your confidence and make you ready to face any questions in CBSE Class 7 examination and competitive examinations.

Download the PDF of the NCERT Exemplar for Class 7 Science Chapter 18 – Wastewater Story

NCERT Exemplar solution class 7 science Chapter 18 1

The Importance of the NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story

NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story cover questions on the importance of water resource, house-keeping practices, sewage and its treatment, sanitation, diseases, the importance of consuming clean water, water pollution, measures to control water pollution, essential diagrams and charts.

Topics Covered in NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story

18.1 – Water, Our Lifeline

18.2 – What Is Sewage?

18.3 – Water Freshens Up – An Eventful Journey

18.4 – Wastewater Treatment Plant

18.5 – Better House Keeping Practices

18.6 – Sanitation and Disease

18.7 – Alternative Arrangement for Sewage Disposal

18.8 – Sanitation at Public Places

Access Answers to the NCERT Exemplar for Class 7 Science Chapter 18 – Wastewater Story

Multiple choice questions.

1. Which of the following is wastewater?

(a) Water trickling from a damaged tap.

(b) Water coming out of a shower.

(c) Water flowing in a river.

(d) Water coming out of laundry.

The answer is (d) Water coming out of laundry.

Explanation:

Water discharged during after routine works like washing clothes, flushing toilet, cleaning utensils makes the water dirty. This water is called as wastewater. Water coming out of the damaged tap, water coming out of shower and water flowing in a river are not dirty hence water coming out of a laundry is the right answer.

2. Sewage is mainly a

(a) liquid waste.

(b) solid waste.

(c) gaseous waste.

(d) mixture of solid and gas.

The answer is (a) liquid waste.

Sewage water is the wastewater that includes domestic and industrial liquid wastes. It contains various suspended solids and harmful microorganisms.

3. Which of the following is/are products of wastewater treatment?

(c) Both biogas and sludge

(d) Aerator

The answer is (c) Both biogas and sludge

During wastewater, treatment water is allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the floatable solids like oil and grease. Water so cleared is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.

4. An open-drain system is a breeding place for which of the following.

(b) Mosquitoes

(c) Organisms which cause diseases

(d) All of these

The answer is (d) All of these

The opening draining system causes problems with the foul smell. The open drainage system is the breeding sources for mosquitos and flies. The open drainage system also helps the growth of disease-causing organisms.

5. Water polluted by various human activities causes a number of water-borne diseases. Which of the following is not a waterborne disease?

(a) Cholera

(b) Typhoid

(d) Dysentry

The answer is (c) Asthma

Asthma is airborne disease whereas Cholera, Typhoid and dysentery are spread by contaminated water and food.

6. Pick from the following one chemical used to disinfect water.

(a) Chlorine

(b) Washing soda

The answer is (a) Chlorine

Chorine is used to killing harmful organisms and the process of adding chlorine is called as chlorination.

7. The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as

(a) sewers.

(b) sewerage.

(c) transport system.

(d) treatment plant.

The answer is (b) sewerage.

8. Which of the following is a part of inorganic impurities of the sewage?

(a) Pesticides

(c) Phosphates

(d) Vegetable waste

The answer is (c) Phosphates

Pesticides, urea and vegetable waste ate the organic waste that acts as impurities in sewage water whereas phosphates are the inorganic impurities present in sewage.

9. In a filtration, plant water is filtered using layers of

(a) sand and clay.

(b) clay and fine gravel.

(c) sand and fine gravel.

(d) sand, fine gravel and medium gravel.

The answer is (d) sand, fine gravel and medium gravel.

During wastewater treatment wastewater is allowed to enter a grit of sand, fine gravel and medium gravel. Here the speed of wastewater is slowed down to allow sand, fine gravel and medium gravel to settle down.

10. Which of the following is not a source of wastewater?

(c) Industries

(d) Hospitals

The answer is (a) Sewers

Sewers are a network of big and small pipes that carries sewage from the point of being produced to the point of disposal, i.e. treatment plant.

Very Short Answer Questions

11. Why are open drains a concern?

Because it creates unhygienic and unsanitary conditions because of which it leads to the spread of disease.

12. State whether the following statements are True or False. In case a statement is false, write the correct statement.

(a) Sewage is a solid waste which causes water pollution and soil pollution.

(b) Used water is wastewater.

(c) Wastewater could be reused.

(d) Where underground sewerage systems and refuse disposal systems are not available, the high-cost on-site sanitation system can be adopted.

a) False- Sewage is a liquid waste which causes water pollution and soil pollution

d) False- Where underground sewerage systems and refuse disposal systems are not available, the low-cost on-site sanitation system can be adopted.

13. How are open drains harmful to human health?

The opening draining system causes problems with the foul smell.  An open drainage system is the breeding sources for mosquitos and flies. The open drainage system also helps the growth of disease-causing organisms. Hence drains are harmful to human health.

Short Answer Questions

14. Name two inorganic impurities present in sewage.

Nitrates, Phosphates

15. Animal waste, oil and urea are some of the organic impurities present in sewage. Name two more organic impurities present in sewage.

Fruits, Vegetables

16. Name two alternative arrangements for sewage disposal where there is no sewerage system.

(i) Septic tanks (ii) Composting pits

17. A man travelling in a train threw an empty packet of food on the platform. Do you think this is a proper waste disposal method? Elaborate.

No, what man does is not a proper disposal method. One must always put the waste in a nearby dustbin or carry it until a proper place to dispose of food packet is found.

18. Why should we not throw

(a) used tea leaves into the sink?

(b) cooking oil and fats down the drain?

a) Used tea leaves may block the sink.

b) Cooking oil and fats gets harden and block the sink.

19. Match the items of Column I with the items of Column II with reference to sewage.

a) Inorganic impurities ii) Nitrates and Phosphates
b) organic impurities iv) Pesticides and Herbicides
c) Nutrients i) Phosphorus and Nitrogen
d) Bacteria iii) Cholera and Typhoid

20. Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence.

(a) Sludge is scraped out and skimmer removes the floating grease.

(b) Water is made to settle in a large tank with a slope in the middle.

(c) Large objects like plastic bags are removed by passing wastewater through bar screens.

(d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.

(e) Wastewater enters a grit and sand removal tank.

21. Three statements are provided here which define the terms –

(b) sewage and

(c) wastewater.

Pick out the correct definition for each of these terms.

(a) The settled solids that are removed in wastewater treatment with a scraper.

(b) Water from the kitchen used for washing dishes.

(c) Wastewater released from homes, industries, hospitals and other public buildings.

22. A mixture (x) in water contains suspended solids, organic impurities, inorganic impurities (a), nutrients

(b), disease-causing bacteria and other microbes. Give names for (x), (a) and (b)?

(a) nitrates, phosphates and metal

(b) phosphorus and nitrogen

Long Answer Questions

23. What are the different types of inorganic and organic impurities generally present in sewage?

(i) Inorganic impurities – nitrates, phosphates and metals.

(ii) Organic impurities – fruit and vegetable wastes, oil, urea, human faeces, animal waste, pesticides and herbicides.

24. The terms sewage, sewers and sewerage are interlinked with each other. Can you explain, how?

The terms ‘sewage, ‘sewers’ and ‘sewerage are interlinked with each other because sewage is a mixture of wastewater coming out of homes and other places. Sewers are pipes which carry sewage and sewerage is a network of sewage carrying pipes.

25. Fill in the blanks in the following statements using words given in the box.

NCERT Exemplar Solutions Class 7 Science Chapter 18 Wastewater Story sol-1

A very _________ number of our people defecate in the open. It may cause _________ pollution and soil pollution. Both the surface water and _________ water get polluted. _________ water is the source for wells, tubewells and _________. Thus it becomes the most common route for _________ borne diseases like _________, dysentery, etc.

A very large number of our people defecate in the open. It may cause water pollution and soil pollution. Both the surface water and ground  water get polluted. Ground water is the source for wells, tube-wells and handpumps . Thus it becomes the most common route for water borne diseases like cholera , dysentery, etc.

26. Describe various steps of cleaning wastewater in a wastewater treatment plant.

Treatment of wastewater involves physical, chemical, and biological processes, which remove physical, chemical and biological matter that contaminates the wastewater.

  • Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.
  • Water then goes to a grit and sand removal tank. The speed of the incoming wastewater is decreased to allow sand, grit and pebbles to settle down
  • The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the floatable solids like oil and grease. Water so cleared is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.
  • Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.

After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top. The activated sludge is about 97% water. The water is removed by sand drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to the soil. The treated water has a very low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Nature cleans it up further. Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

27. Think and suggest some ways to minimise waste and pollutants at their source, taking your home as an example.

(i) Do not throw used tea leaves, solid food remains, etc. in the drain. Throw them in the dustbin.

(ii) Chemicals like medicines, paints, insecticides, etc. should not be thrown in the drain, as they increase the pollution load of the sewage.

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Frequently Asked Questions NCERT Exemplar for Class 7 Science Chapter 18 Wastewater Story

Why are open drains a concern.

The reason for the concern is that it creates unhygienic and unsanitary conditions, which leads to the spread of disease.

How are open drains harmful to human health?

The opening draining system causes a foul smell. It is a breeding source for mosquitos and flies. Besides, an open drainage system leads to the growth of disease-causing organisms. Hence, it is harmful to human health.

Name two inorganic impurities present in sewage.

Nitrates and phosphates

Animal waste, oil and urea are some of the organic impurities present in sewage. Name two more organic impurities present in sewage.

Fruits and vegetables

Name two alternative arrangements for sewage disposal where there is no sewerage system.

A person travelling on a train threw an empty food packet on the platform. do you think this is a proper waste disposal method elaborate..

No, what the person did was not a proper disposal method. One must always put the waste in a dustbin or carry it until a proper place for waste disposal is found.

What are the different types of inorganic and organic impurities generally present in sewage?

(i) Inorganic impurities – Nitrates, phosphates and metals.

(ii) Organic impurities – Fruit and vegetable wastes, oil, urea, human faeces, animal waste, pesticides and herbicides.

The terms sewage, sewers and sewerage are interlinked with each other. Can you explain how?

The terms ‘sewage, ‘sewers’ and ‘sewerage are interlinked with each other because sewage is a mixture of wastewater coming out of homes and other places. Sewers are pipes which carry sewage, and sewerage is a network of sewage-carrying pipes.

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Extra Questions for Class 7 Science with Answers

Extra Questions for Class 7 Science with Answers help to score good marks in the CBSE exam. We prepared these Questions as per the latest Class 7 Science NCERT book. These extra questions come from all the enriched concepts from the chapters of science. Science is one of the main subjects of higher secondary and higher classes. Scoring well in Science examinations not only improves your academic records but gives you the confidence to pursue a career in the field of Science. Practicing these will help students to score good marks in the examination.

Extra Questions for Class 7 Science – List of Chapters

  • Chapter 1 – Nutrition in Plants
  • Chapter 2 – Nutrition in Animals
  • Chapter 3 – Fibre to Fabric
  • Chapter 4 – Heat
  • Chapter 5 – Acids, Bases and Salts
  • Chapter 6 – Physical and Chemical Changes
  • Chapter 7 – Weather, Climate And Adaptations of Animals To Climate
  • Chapter 8 – Winds, Storms And Cyclones
  • Chapter 9 – Soil
  • Chapter 10 – Respiration In Organisms
  • Chapter 11 – Transportations In Animals And Plants
  • Chapter 12 – Reproduction In Plants
  • Chapter 13 – Motion And Time
  • Chapter 14 – Electric Current And Its Effects
  • Chapter 15 – Light
  • Chapter 16 – Water: A Precious Resource
  • Chapter 17 – Forests: Our Lifeline
  • Chapter 18 – Wastewater Story

Class 7 Science Extra Questions and Answers

These questions are created by the subject experts based exclusively from the exam perspective. Students must start solving them at least one month before the annual exam. By doing so, they will be able to analyse their weak areas. Working on them will improve their performance and overall score in CBSE Class 7 Science exam.

NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12

Wastewater Story Class 7 Extra Questions Science Chapter 18

June 7, 2019 by Sastry CBSE

Wastewater Story Class 7 Science Extra Questions Very Short Answer Type Questions

Question 1. Wastewater is fit for human consumption or not. Give reason to support your answer. Answer: No, because it is dirty and has many diseases causing organisms like cholera, typhoid, etc.

Question 2. Name two chemicals used to disinfect wastewater. Answer: Chlorine and ozone.

Question 3. Special type of toilets has been designed in aeroplanes, name it. Answer: Vacuum toilets.

Question 4. Name the toilets used in areas with limited water supply. Answer: Vermi-processing toilets.

Question 5. Name the type of toilets which are most suitable for holding an outdoor music festival in a park. Answer: Chemical toilets.

Question 6. Name two things that can be made from sludge extracted during treatment of sewage. Answer: Biogas and manure.

Question 7. The Eucalyptus trees are planted along sewage ponds. Give reason. [HOTS] Answer: The Eucalyptus trees are planted along sewage ponds because these trees absorb all surplus wastewater rapidly and release pure water vapour into the atmosphere.

Question 8. One can avoid the addition of the load in WWTP. Justify. Answer: By following proper sanitation and house-keeping practices, by creating less waste at an individual level, we can avoid the addition of the load in wastewater treatment plant.

Question 9. Name two inorganic impurities present in sewage. [NCERT Exemplar] Answer: Inorganic impurities present in sewage are nitrates and phosphates.

Question 10. Mention the use of dried sludge. Answer: It is used as manure, thus returning organic matter and nutrients to the soil.

Question 11. In which type of toilets, human excreta is treated by earthworm? Answer: Vermi-processing toilets.

Question 12. Give some examples of onsite sewage disposal systems. Answer: Chemical toilets, septic tanks, composting pits, etc.

Question 13. Sewage contains some organic impurities in it. Name them. Answer: Human faeces, animal wastes, oil, urea pesticides, herbicides, fruits and vegetables are the organic impurities present in sewage.

Question 14. Mention the common process of cleaning of wastewater. Answer: Sewage treatment.

Question 15. World Water Day is celebrated on Answer: 22 March.

Question 16. Mention the period proclaimed as the International Decade for action on Water for Life. Answer: 2005-2015 is the period proclaimed as the International Decade for action on Water for Life.

Question 17. Name the three processes involved in treatment of wastewater. Answer: Treatment of wastewater involves physical, chemical and biological processes for removing different types of contaminants.

Question 18. Explain sewers and sewage. Answer: Sewers are the pipes acting as a transport system that carries sewage from point of origin to the point of disposal. The wastewater released from homes, industries, hospitals, offices and other uses is called sewage.

Question 19. The used water should not be wasted. Do you agree? Justify. Answer: The used water should not be wasted but it should be cleaned.

Question 20. Bleaching powder is mixed in water, why? Think and give appropriate reason for it. [HOTS] Answer: Bleaching powder is mixed in water to make it safe for drinking because it kills the harmful germs present in water.

Question 21. Natural water is the purest form of water. Explain why or why not. Answer: Natural water is not pure always. It is because all types of water except rainwater contain salts dissolved in it. These salts make the water impure.

Question 22. Mention the role of effluent treatment plants in cities. Answer: The effluent treatment plants filter out undissolved materials form water.

Question 23. Protozoa is causative organism of which waterborne disease? Answer: Dysentry.

Question 24. In the chemical process of water treatment, water is treated with some chemicals. Describe chlorination in light of it. [HOTS] Answer: Chlorination is the process of adding chlorine (chemical) in water to make it safe for drinking.

Question 25. Sanitation can be improved. Explain, what step should be taken to improve it. Answer: Low cost onsite sewage disposal system must be encouraged to improve sanitation.

Question 26. Give the percentage of water being activated in sludge. Answer: About 97% of water is being activated in sludge.

Question 27. Animal waste, oil and urea are some of the organic impurities present in sewage. Name two more organic impurities present in sewage. [NCERT Exemplar] Answer: Fruits and vegetable wastes, pesticides and herbicides are organic impurities present in sewage other than animal wastes, oil and urea.

Wastewater Story Class 7 Science Extra Questions Short Answer Type Questions

Question 1. Open drain is a big concern now-a-days. Justify. Answer: Open drain is a big concern for the society now-a-days because they create unhygienic conditions. It provides favourable conditions to flies, mosquitoes and other insects to breed and spread a number of diseases.

Question 2. Explain, how sewage is disposed of in an aeroplane. Answer: Aeroplanes have their closed waste sewage tanks in them, which suck the wastewater and collect it in their tanks. Once the aeroplane lands on the ground, the crew disposed of the sewage properly into airport sewage facility.

Question 3. Sewage also contains some nutrients Comment. Answer: Sewage is a complex mixture which contains suspended solids, organic and inorganic impurities, nutrients, saprotrophic and disease causing bacteria and other microbes. The nutrients present in sewage are phosphorus and nitrogen.

Question 4. Suggest two alternative arrangements for sewage disposal where there is no sewerage system. Answer: The two alternative arrangements for sewage disposal, where there is no sewerage system are as below

  • Septic tanks
  • Composting pits.

Question 5. Recall and enlist some better house keeping practices. Answer: We must minimise and manage waste at our houses before its disposal in the following manner:

  • Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain the fats clog the soil pores reducing its effectiveness in filtering water. Throw oil and fats in the dustbin.
  • Used tealeaves, solid food remains, soft toys, cotton, sanitary towels, etc., should also be thrown in the dustbin. These wastes choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.
  • The chemicals like paints, solvents, insecticides, medicines and motor oils should 1 State the role of screen bars in wastewater treatments, not be thrown in drains as they kill helpful 2 Chlorination makes water fit for human consumption. How? microbes which digest the organic waste.

Question 6. Water in a river is cleaned naturally. Do you agree? Think and explain. [HOTS] Answer: Yes, river water is cleaned naturally by a process that is similar to wastewater treatment plant. As muddy water when flows through grass or weeds on its way to a stream, mud and solid particles get filtered out. At the bottom of a lake or stream, microorganism brings chemical changes in the water. The natural filtration process removes pollution from the roundwater throughout the process making it clean and fit for drinking.

Question 7. The terms sewage, sewers and sewerage are interlinked with each other. Can you explain, how? [NCERT Exemplar] Answer: The terms like sewage, sewers and sewerage are interlinked with each other because sewage is a mixture of wastewater coming out of homes and other places. Sewers are pipes which carry sewage and sewerage is a network of sewage carrying pipes.

Question 8. Describe onsite disposal systems. Answer: Some organisations offer hygienic onsite human waste disposal technology. These toilets do not require scavenging. Excreta from the toilet seats flow through covered drains into a biogas plant. The biogas produced is used as a source of energy.

Question 9. A sewage treatment plant involves few steps in its working. Aeration tank, grit and sand removal tank, second sedimentation tank, bar screen, first sedimentation tank. (a) Arrange all the above steps in the correct order in which they occur in the sewage treatment plant. (b) Which step gives most of the sludge? [HOTS] Answer: (a) Bar screen, grit and sand removal tank, first sedimentation tank, aeration tank, second sedimentation tank. (b) First sedimentation tank.

Question 10. Give reasons for each of the following. (a) We should not throw used tea leaves into sink. (b) We should not throw cooking oil and fats down the drain. [NCERT Exemplar] Answer: (a) We should not throw used tea leaves into sink because it may choke the drain-pipe of the sink. (b) We should not throw cooking oil and fats down the drain as it can harden and block the drain-pipes.

Question 11. Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence. (a) Sludge is scraped out and skimmer removes floating grease. (b) Water is made to settle in a large tank with a slope in the middle. (c) Large objects like plastic bags are removed by passing wastewater through bar screens. (d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater. (e) Wastewater enters a grit and sand removal tank. {NCERT Exemplar] Answer: The correct sequence of wastewater treatment in treatment plant is (c) Large objects like plastic bags are removed by passing wastewater through bar screens. (e) Wastewater enters a grit and sand removal tank. (d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater. (b) Water is made to settle in a large tank with a slope in the middle. (a) Sludge is scraped out and skimmer removes the floating grease.

Question 12. Can we contribute in sanitation at public places? Explain. Answer: Yes, we all have a role to play in keeping our environment clean and healthy. All of us can contribute in maintaining sanitation at public places. 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.

Question 13. Three statements are provided here which define the terms, i.e. sludge, sewage and wastewater. Pick out the correct definition for each of these terms. (a) The settled solids that are removed in wastewater treatment with a scraper. (b) Water from kitchen used for washing dishes. (c) Wastewater released from homes, industries, hospitals and other public buildings. [NCERT Exemplar] Answer: (a) The settled solids that are removed in wastewater treatment with a scraper is sludge. (b) Water from kitchen which is used for washing dishes is wastewater. (c) Wastewater released from homes, industries, hospitals and other public buildings is sewage.

Question 14. A man travelling in a train threw an empty packet of food on the platform. Do you think this is a proper waste disposal method? Elaborate. [NCERT Extmplar; HOTS] Answer: No, one must always put the waste in a nearby dustbin or carry it home and dispose it in dustbins there. Waste, not properly disposed may enter into the drains and choke them. It also makes public places dirty and unhygienic.

Question 15. With reference to the treatment of polluted water at home by aeration, filtration, chlorination processes answer the following questions. (a) What changes did we observe in the appearance of liquid after aeration? Did aeration change the odour? (b) What is removed by the sand filter? (c) Does chlorine change the colour of treated water? (d) Do chlorine have an odour? Answer: (a) Aerated water contains some suspended impurities and the foul odour of the polluted water disappears completely after aeration. (b) Sand filter removes tiny suspended impurities. (c) Chlorine makes the water clear and colourless. (d) Yes, chlorine have a peculiar odour which is not worse than wastewater.

Wastewater Story Class 7 Extra Questions Science Chapter 18 1

  • River It is the source of water.
  • Pumping station Pump the water to collect it in reservoir.
  • Sedimentation tank Impurities are settle in the bottom of tank.
  • Sand and gravel and sand filter Remove the dirt from the water.
  • Chlorinating tank Chlorine is mixed in water to disinfect the eater and to kill the germs.
  • To overhead tank Purified water is stored in this tank for supply to the households for drinking.

Question 17. Complete .the table given below of the contaminant survey.

T
Sullage water Kitchen
Foul waste Toilets
Trade waste Industrial and commercial organisations

Answer: Given below is the table of contaminant survey explaining types of sewage with their point of origin an contaminate in them.

Sullage water Kitchen Cooking oils, fats, etc. May choke drains
Foul waste Toilets Faeces and urine Cause diseases like dysentery, cholera, etc
Trade waste Industrial and commercial organisations Chemicals like paints, solvents, motor oil, etc. Causes water and soil pollution

Wastewater Story Class 7 Science Extra Questions Long Answer Type Questions

Question 1. Explain the different types of inorganic and organic impurities generally present in sewage. Answer: It is wastewater released by homes, industries agricultural fields and other human activities. It also includes rainwater that has run down the street during a storm or heavy rain and it is a liquid waste. Most of its water has dissolved and suspended impurities called contaminants. Composition of Sewage The following components make the sewage:

  • The organic impurities present in sewage are human faeces, animal wastes (like animal dung), urea (as urine), oil, fruits and vegetable wastes, pesticides, herbicides, etc.
  • The inorganic impurities present in sewage are nitrates, phosphates and metals.
  • The nutrients present in sewage are nitrogen and phosphorus.
  • The bacteria present in sewage include those bacteria which cause water-borne diseases such as cholera and typhoid.
  • The other microbes present in sewage are Protozoa which cause a water-borne disease called dysentery.

Question 2. Describe septic tank. How does it function? Answer: Low cost outside sewage disposal system have been developed to take care of places where there is no sewage system, e.g. rural areas, isolated buildings. These are described below: (i) Septic tanks Septic tank is a low cost onsite sewage disposal system. Septic tanks are suitable where there is no sewerage made. These tanks need cleaning every four to six months.

A septic tank usually consists of a big, covered underground tank made of concrete having an inlet pipe at one end and on outlet pipe at the other end. The toilet seat is connected to the inlet pipe of the septic tank. The human excreta from the toilet seat enters into the septic tank through the inlet pipe. The solid part of excreta keeps on collecting at the bottom of the septic tank in the form of a sludge whereas watery waste remains above it.

The anaerobic bacteria breakdown most of the solid organic matter present in human excreta due to which the volume of solid waste is reduced too much. The digested solid waste keeps on depositing at the bottom of septic tank. The watery waste is also cleaned by anaerobic bacteria. The excess water goes out of the septic tank through the outlet pipe and get absorbed in soil.

(ii) Composting pits These are self sustained human waste disposal units which is not connected to a sewer line or a septic tank. A composting toilet breaks down and dehydrate human waste to compost.

(iii) Chemical toilets These toilets have limited storage capacity for human waste and need to be emptied periodically. These are the toilets which use chemically treated reservoir located just below the toilet seats. The chemicals reduce the foul smell coming out of human excrete and carry out partial disinfection of human waste.

Question 3. Discuss vermi-processing toilets. Name the useful product obtained from such toilets. Answer: In the vermi-processing toilet, the human excreta is treated by earthworms in a pit. The earthworms gradually eat up all the organic matter present in human excreta, decompose it and pass out from their body in the form of warm casting (also called vermi cakes). The useful product obtained from a vermi-processing toilet is vermi cakes which is kind of high quality manure.

Question 4. One day Sachin had gone to his uncle who lives in a village. He saw there a large number of people defecate in an open area because proper toilet facilities are not there. He wondered about the groundwater contamination, as he studied in his class that this act may cause water-borne diseases. He convinced village people to make toilets to avoid such an out break of water-borne diseases. (a) Name two water-borne diseases. (b) Explain vermi-composting toilets. (c) What values are shown by Sachin? [Value Based Question] Answer: (a) Typhoid and cholera. (b) In vermi-composting toilets, human excreta is treated by earthworms in a pit. (c) He is intelligent and concious about health.

Question 5. There are many alternative sewage disposal systems which have been developed as per needs of the community, persons, occasions, etc.. Few situations/specifications of the sewage need are given below. Write the name of sewage which can be used in the following conditions. (a) A toilet which can provide high quality manure. (b) The toilet which is used in aeroplane during flight. (c) A toilet which can be used in some out door gathering. (d) A toilet used in limited water supply. (e) A toilet which contaminates water of hand pump installed nearby. [HOTS] Answer: (a) Vermi-composting toilets (b) Vacuum toilets (c) Chemical toilets (d) Composting toilets (e) Septic tank toilets

Question 6. Think and suggest some ways to minimise waste and pollutants at their source, taking your home as an example. Answer: We can minimise waste and pollutants entering the water and create less wastewater by taking following few steps at home:

  • By not throwing used tea leaves, solid food remains, etc., in the drain. We should throw it in the dustbin.
  • By not throwing chemicals like medicines, paints, insecticides, etc., in the drain as they increase the pollution load of the sewage.

Question 7. Trisha has seen huge garbage dumps outside the school campus which are not being regularly disposed of by municipality of the area. She discussed the problem with her biology teacher and decided to organise a rally to spread awareness among local people. Next day she delivered this information in the assembly and convinced the school mates to join her. She also explained them about the importance of sanitation at public places which she had recently studied in biology. (a) In your views, who is responsible to maintain sanitation at public places? (b) What would happen, if all the wastes produced at public places are not disposed of regularly? (c) What are the valuesS shown by Trisha? [Value Based Question] Answer: (a) In my opinion, municipality is responsible to maintain sanitation at public places. (b) If all the wastes produced at public places are not disposed of regularly and properly epidemics could break out. (c) Responsibility, sensitivity and awareness towards public hygiene.

Wastewater Story Class 7 Science Extra Questions Miscellaneous Questions

Multiple Choice Questions Question 1. Open drain system is a breeding place for which of the following? [NCERT Exemplar] (a) Flies (b) Mosquitoes (c) Organisms which cause diseases (d) All of the above Answer: (d) All of the above

Question 2. Which of the following is not an inorganic impurity present in sewage? (a) Nitrate (b) Phosphorus (c) Urea (d) Metal salt Answer: (c) Urea

Question 3. Sewage is mainly a [NCERT Exemplar] (a) liquid waste (b) solid waste (c) gaseous waste (d) mixture of solid and gas Answer: (a) liquid waste

Question 4. The aerobic bacteria can be grown in clarified water by (a) filtration (b) sewage (c) aeration (d) sedimentation Answer: (c) aeration

Question 5. Which of the following is/are products of wastewater treatment? [NCERT Exemplar] (a) Biogas (b) Sludge (c) Both biogas and sludge (d) Aerator Answer: (c) Both biogas and sludge

Question 6. Chlorine is used in municipal water treatment plant to (a) change the teste of water (b) prevent evaporation (c) kill the harmful microorganisms (d) prevent sedimentation Answer: (c) kill the harmful microorganisms

Question 7. Which of the following organisms produce biogas from sludge in the digester tank of a wastewater treatment plant? (a) Anaerobic bacteria (b) Fungi (c) Aerobic bacteria (d) Protozoa Answer: (a) Anaerobic bacteria

Question 8. The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as [NCERT Exemplar] (a) sewers (b) sewerage (c) transport system (d) treatment plant Answer: (b) sewerage

Question 9. One of the following type of trees are said to help in purifying wastewater quite rapidly when planted all along the sewage ponds. These are (a) Eucalyptus trees (b) Ficus trees (c) neem trees (d) peepal trees Answer: (a) Eucalyptus trees

Question 10. Which of the following is a part of inorganic impurities of the sewage? [NCERT Exemplar] (a) Pesticides (b) Urea (c) Phosphates (d) Vegetable waste Answer: (c) Phosphates

Question 11. Which of the following statements about ozone are correct? I It is essential for breathing of living organisms. II It is used to disinfect water. III It absorbs ultraviolet rays. IV Its proportion in air is about 3%. (a) I and II (b) II and III (c) I and III (d) II and IV Answer: (b) II and III

Question 12. In a filtration plant, water is filtered using layers of (a) sand and clay (b) clay and fine gravel (c) sand and fine gravel (d) sand, fine gravel and medium gravel Answer: (d) sand, fine gravel and medium gravel

Question 13. Which one of the following is a quality of wastewater? (a) Fowl smell (b) Bad taste (c) Dirty look (d) All of these Answer: (d) All of these

Question 14. Period 2005-2015 is being celebrated as the international decade for action on (a) water for life (b) education for all (c) global warming (d) terrorism Answer: (a) water for life

Question 15. In sewerage main holes are located at every (a) 20-25 m (b) 50-60 m (c) 90-100 m (d) 100-110 m Answer: (b) 50-60 m

Question 16. Which of these is a part of the wastewater treatment plant? (a) Clarifier (b) Vertical bars (c) Aeration tank (d) All of these Answer: (d) All of these

Question 17. Which of these methods should not be used for disposal of urine and faeces if no sewage system is available? (a) Allowing untreated sewage to flow into rivers (b) Making septic tanks for sewage to flow into (c) Allowing sewage to flow into a biogas plant (d) Using a vermi-composting toilet Answer: (a) Allowing untreated sewage to flow into rivers

Fill in the Blanks 1. Untreated human excreta is a ………………. hazard. 2. Vermi-composting toilets use ………………. to treat human waste. 3. Poor sanitation is crowded public places can result in spread of ………………. . 4. Dried sludge is used as ………………. . 5. Wastewater is treated in ………………. treatment plant. 6. Wastewater released by houses is called ………………. . 7. Stagnant water blocked in drains is good breeding place for ………………. . 8. All portable toilets are ………………. toilets. 9. The full form of WWTP is ………………. . 10. Bacteria play important ………………. in sewage treatment. Answers: 1. health 2. earthworms 3. diseases 4. sludge activator 5. waste 6. sewage 7. insect vectors 8. chemical 9. wastewater treatment plant 10. role

True/False 1. Sewage is a solid waste which causes water pollution and soil pollution. [NCERT Exemplar] 2. Used water is wastewater. 3. Wastewater could be reused. 4. Where underground sewerage systems and refuse disposal systems are not available, the high cost onsite sanitation system can be adopted. [NCERT Exemplar] 5. We should not defecate is open because untreated human waste is a health hazard. 6. Cooking oil, fats should not be thrown in the drainage system directly. 7. Microorganisms are present in the domestic waste also. 8. Poor sanitation and contaminated drinking water is the cause of a large number of diseases. 9. Wastewater is transparent, colourless, odourless. 10. Tuberculosis is a water-borne disease. 11. Aerobic bacteria produces biogas sludge in the digester tank. 12. urea is an inorganic impurity present in sewage. Answers: 1. False, sewage is a liquid waste which causes water pollution and soil pollution. 2. True 3. True 4. False, where underground sewerage systems and refuse disposal systems are not available, the low cost onsite sanitation system can be adopted. 5. True 6. True 7. True 8. True 9. False, potable water is transparent, colourless and odourless. 10. False, water-borne diseases are cholera, typhoid, dysentery, etc. 11. False, anaerobic bacteria produce biogas. 12. False, urea is an organic impurity present in sewage.

Match the Columns Question 1. Match the Column I with Column II.

(a) Inorganic impurities (i) Phosphorus and nitrogen
(b) Organic impurities (ii) Nitrates and phosphates
(c) Nutrients (iii) Cholera and typhoid
(d) Bacteria (iv) Pesticides and herbicides

Answers: 1. (a)-(ii) (b)-(iv) (c)-(i) (d)-(iii)

Extra Questions for Class 7 Science

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Class 7 Science Case Study Question and Answer: CBSE / NCERT Board Class 7 Science Case Study Question prepared by expert Science Teacher. Students can learn Case Based Question / Paragraph Type Question for NCERT Class 7 Science.

There are total 18 chapter Nutrition in Plants, Nutrition in Animals, Fibre to Fabric, Heat, Acids, Bases and Salts, Physical and Chemical Changes, Weather, Climate and Adaptations of Animals to Climate, Winds, Storms and Cyclones, Soil, Respiration in Organisms, Transportation in Animals and Plants, Reproduction in Plants, Motion and Time, Electric Current and Its Effects, Light, Water: A Precious Resource, Forests: Our Lifeline, Wastewater Story

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CBSE Class 7 Science Case Study Question

  • Chapter 1 Nutrition in Plants Case Study Question
  • Chapter 2 Nutrition in Animals Case Study Question
  • Chapter 3 Fibre to Fabric Case Study Question
  • Chapter 4 Heat Case Study Question
  • Chapter 5 Acids, Bases and Salts Case Study Question
  • Chapter 6 Physical and Chemical Changes Case Study Question
  • Chapter 7 Weather, Climate and Adaptations of Animals to Climate Case Study Question
  • Chapter 8 Winds, Storms and Cyclones Case Study Question
  • Chapter 9 Soil Case Study Question
  • Chapter 10 Respiration in Organisms Case Study Question
  • Chapter 11 Transportation in Animals and Plants Case Study Question
  • Chapter 12 Reproduction in Plants Case Study Question
  • Chapter 13 Motion and Time Case Study Question
  • Chapter 14 Electric Current and Its Effects
  • Chapter 15 Light
  • Chapter 16 Water: A Precious Resource
  • Chapter 17 Forests: Our Lifeline
  • Chapter 18 Wastewater Story

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Most of time 5 questions will made from each case. There will 1 or 2 marks for each question.

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  • NCERT Class 7 Math Solution

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  1. Case Study Questions Class 7 Science Wastewater Story

    At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks. CBSE Case Study Questions Class 7 Science Wastewater Story Case study 1. All of us use water in our homes and make it dirty.

  2. Extra Questions for Class 7 Science Chapter 18 Wastewater Story

    Answer: Cleaning of water is a process of removing pollutants before it enters a water body or is reused. This process of wastewater treatment is commonly known as "Sewage Treatment". It takes place in several stages. 9. Explain the function of bar screens in a wastewater treatment plant.

  3. NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

    Chapter 18 of NCERT Solutions for Class 7 Science guides students in segregating waste which leads to a 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.

  4. Important Questions for CBSE Class 7 Science Chapter 18

    Show more courses. Study Important Questions for Class 7 Science Chapter 18 - Waste Water Story. Very Short Answer Questions: (1 Marks) Fill in the Blanks: 1. The United Nations declared the period from 2005-2015 as the International Decade for _______________. Ans: Action on the water for life. 2.

  5. NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

    Ans. Following steps are involved in the purification of water: (i) Firstly all the physical impurities like stones, plastic bags, cans etc. are to be 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.

  6. NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

    NCERT Class 7 Science Chapter 18 Wastewater Story Exercises Solution. 1. Fill in the blanks: Cleaning of water is a process of removing impurities. Wastewater released by houses is called sewage. Dried sludge is used as manure. Drains get blocked by oils and fats. 2.

  7. MCQ Questions for Class 7 Science Chapter 18 Wastewater Story with

    Question 12. The equipment that removes floatable particles from wastewater is. (a) sludge. (b) bar screen. (c) skimmer. (d) sedimentation tank. Answer. Question 13. The tree that helps in wastewater treatment by absorbing water greatly and releasing pure water in environment through transpiration is.

  8. Wastewater Story Important Questions Class 7 Science Chapter 18

    Answer: bacteria and microbes. 18: Name the chemical used in water plant to clean water. Answer: Chlorine tablets or ozone. 19: Dried _ is used as manure. Answer: Sludge. 20: List the substances responsible for blockage of drain. Answer: Tealeaves, solid food remains, soft toys, cotton, and sanitary towels.

  9. NCERT Solutions for Class 7 Science Chapter 18 Wastewater ...

    Form a Study Group: To rectify the mistakes after solving Chapter 18 Wastewater Story questions from the NCERT Class 7 Science Solutions, students need to make study groups. Through making study groups, students can set a learning goal to practise Science Chapter 18 Wastewater Story questions.

  10. NCERT Exemplar Class 7 Science Chapter 18 Wastewater Story

    Solution: (a) During wastewater treatment, disinfectant like chlorine is added to the water to kill harmful microorganisms. Question 7. The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as. (a) sewers. (b) sewerage.

  11. NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

    NCERT solutions for Class 7 Science, Chapter 18, or any other chapter, offer several advantages: 1. Aligned with Curriculum: NCERT solutions are designed to be in sync with the CBSE curriculum. They cover the topics and concepts outlined in the official curriculum, ensuring that students are well-prepared for exams. 2.

  12. Important Questions Class 7 Science Chapter 18

    The questions from our Important Questions Class 7 Science Chapter 18 will be based on all aspects of the chapter, including all topics. This helps students to self-assess their knowledge and understanding of various topics and revise those topics they are weak in and enhance the clarity of concepts that can help them in higher studies as well. .

  13. Download the PDF of the NCERT Exemplar for Class 7 Science Chapter 18

    The Importance of the NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story. NCERT Exemplar Solutions for Class 7 Science Chapter 18 Wastewater Story cover questions on the importance of water resource, house-keeping practices, sewage and its treatment, sanitation, diseases, the importance of consuming clean water, water pollution, measures to control water pollution ...

  14. Extra Questions for Class 7 Science with Answers

    Extra Questions for Class 7 Science - List of Chapters. Chapter 1 - Nutrition in Plants. Chapter 2 - Nutrition in Animals. Chapter 3 - Fibre to Fabric. Chapter 4 - Heat. Chapter 5 - Acids, Bases and Salts. Chapter 6 - Physical and Chemical Changes. Chapter 7 - Weather, Climate And Adaptations of Animals To Climate.

  15. Wastewater Story Class 7 Extra Questions Science Chapter 18

    Question 1. Wastewater is fit for human consumption or not. Give reason to support your answer. Answer: No, because it is dirty and has many diseases causing organisms like cholera, typhoid, etc. Question 2. Name two chemicals used to disinfect wastewater. Answer:

  16. Class 7 Science Case Study Question

    CBSE Class 7 Science Case Study Question. Chapter 1 Nutrition in Plants Case Study Question. Chapter 2 Nutrition in Animals Case Study Question. Chapter 3 Fibre to Fabric Case Study Question. Chapter 4 Heat Case Study Question. Chapter 5 Acids, Bases and Salts Case Study Question. Chapter 6 Physical and Chemical Changes Case Study Question.

  17. Category: Case Study Questions for Class 7 Science

    12 months ago July 22, 2023 Physics Gurukul 1 Comment on Case Study Questions for Class 7 Science Chapter 14 Electric Current and Its Effects. ... 2023 Physics Gurukul Leave a Comment on Case Study Questions for Class 7 Science Chapter 7 Weather Climate and Adaptation of Animals to Climate.

  18. Case Study Questions Class 7 Science

    Answer Key. Que. 1) (d) Food. Que. 2) (c) Photosynthesis. Que. 3) (b) Complex. Que. 4) Answer: Digestion is process of breakdown of complex food substances into simpler substances. Que. 5) Answer: Animals get their food by either eating plants or by eating animals who depends on plants for their nutrition.

  19. Case Study Questions for Class 7 Science Chapter 15 Light

    [Download] Case Study Questions for Class 7 Science Chapter 15 Light Here we are providing case study or passage-based questions for class 7 science chapter 15 Light. Case Study/Passage Based Questions Passage-1 Lenses are transparent and light can pass through them. Lenses are classified as convex lens and concave lens and we can distinguish between … Continue reading Case Study Questions ...

  20. Case Study Questions Class 7 Science Nutrition in Plants

    Que. 4) Answer: Algae is the other organism which can form its own food through a process called photosynthesis. Que. 5) Answer: green patches are formed in the pond due to the uncontrolled growth of algae and algae are green in colour. CBSE Class 7 Case Study Questions Class 7 Science Chapter 2 Nutrition in Plants.

  21. Case Study Questions Class 7 Science

    At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks. CBSE Case Study Questions Class 7 Science Forests: Our Lifeline Case study 1. One evening Boojho entered thepark with an elderly ...