Wastewater Story NCERT Solutions – Class 7 Science

When you are looking for reliable study material to solve questions given in the NCERT Class 7 Science Chapter 18, check out NCERT Solutions for Class 7 Science Chapter 18 by Extramarks. The solutions are prepared by subject matter experts at Extramarks who meticulously curate answers that comply with the latest CBSE guidelines.

The questions given at the end of every chapter in NCERT books are important from an exam preparation perspective, therefore, students should never skip them. By referring to NCERT Solutions by Extramarks, students can be rest assured that they have accurate answers to all the questions. The solutions can also work as last-minute revision material to master the topic and get better results.

NCERT Solutions for Class 7 Science Chapter 18 

Access NCERT Class 7 Science Chapter 18 – Wastewater Story

NCERT Solution of Class 7 Subject Science Chapter 18

In today’s hectic  schedule, it is  not easy for parents to dedicate  their time to their children’s  studies and exams.  As a result, the child’s performance may suffer. But with Extramarks’ NCERT Solutions for Class 7, students can study  themselves without  any assistance. This is because NCERT Solutions for Class 7 Science Chapter 18 are self-explanatory, easy to understand and complete in every way. . All  students irrespective of  their level will be able to grasp the concept and will  answer any question easily. This encourages the students to master the topic and increase their confidence in achieving a higher grade. 

NCERT Solution Class 7 Science Chapter 18

Wastewater Story is an important chapter in  Class 7 because it tells us about the importance of water as a resource. Not only humans but every living creature on this earth is dependent on it. Water touches upon an important issue of water pollution and how it can eventually become a life-threatening problem for everyone. The chapter explains how clean water transforms into dirty water, and what are the steps or measures that must be taken to reuse and recycle wastewater. 

The chapter also brings forward the issue of contamination of natural resources of water and its consequences. It discusses the activities that cause water pollution and how this is impacting the health of individuals. The chapter discusses the implementation of the Wastewater Treatment Plant to reduce the level of pollutants in nature, the adoption and implementation of low-cost, on-site sanitation systems, the consequences of open drainage systems, and other topics related to water pollution.

NCERT Solutions for Class 7 Science Chapter 18 have answers to textbook questions around topics like – how water can be recycled and treated, segregation of waste to reduce water pollution, sewage, sanitation system and ecosystem balance through water. These answers have been developed by  subject matter experts with the intent to provide nothing but the best learning material  to the students. Hence, making NCERT Solution Class 7 Science Chapter 18 by Extramarks the most simple, authentic and reliable  learning material for improving their score l in the examinations. 

NCERT Solutions for Class 7 Science Chapter 18 – Marks Distribution

 This chapter is important since four or eight marks questions are regularly asked from this chapter in the term and annual exams. The topics that students must cover  from this chapter are as follows:

  • Water – Our Lifeline
  • What is Sewage?
  • The Journey of Water
  • Wastewater Treatment
  • Good housekeeping practises
  • Sanitation and Diseases
  • Sewage Disposal Alternatives
  • Sanitation Practices in Public Places

Benefits of Class 7 Science Chapter 18 Solutions

Benefits of Class 7 Science chapter 18 Solutions are as follows:

  • NCERT Solutions for Class 7 Science chapter 18 make learning a lot easier and help you understand basic concepts of the chapter quickly and effectively. 
  • Solutions have Class 7 Science Chapter 18 question answers and help students gain knowledge about the chapter in the simplest way. When the students study from it, they will definitely have an edge over their peers.
  • Solutions are prepared by the experienced faculty  as per the  CBSE guidelines.

Q.1 Fill in the blanks:
(a) Cleaning of water is a process of removing _________.
(b) Wastewater released by houses is called _________.
(c) Dried _________ is used as manure.
(d) Drains get blocked by _________ and _________.

Ans- 

(a) Cleaning of water is a process of removing pollutants.
(b) Wastewater released by houses is called sewage.
(c) Dried sludge is used as manure.
(d) Drains get blocked by cooking oil and fats.

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

Ans- 

Sewage is wastewater having dissolved and suspended impurities released from homes, industries, hospitals, offices and other users.

It is harmful to discharge untreated sewage into rivers or seas because:

1. Untreated sewage contaminates seas and rivers.
2. Sewage contains various contaminants including disease causing bacteria and other microorganism. Disease causing bacteria and other microorganism may cause dysentery, cholera, typhoid, etc.
3. Pesticide, herbicides present in the sewage may cause various disorders in living beings.

Therefore, it is harmful to discharge untreated sewage into rivers or seas.

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

Ans- 

Oils and fats should not be released in the drain because they can harden and block the pipes. In an open drain the fats clog the soil pores which affect its water filtering efficiency. Therefore, oils and fats should be thrown in dustbins.

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

Ans- 

Steps involved in getting clarified water from wastewater are as follows:

1. Wastewater is passed through bar screens. Large objects like rags, plastic packets and napkins are separated by passing water through bar screens.
2. Water is then passed through grit and sand removal tank. Here, water is passed at a slow speed to allow pebbles and grit to settle down.
3. Water is then allowed to settle in a large tank which is sloped towards the middle. Here, solid wastes like faeces settle down at the bottom. These solid wastes are called sludge. Sludge is removed with a scraper. A skimmer removes the floating wastes like oil and grease. Water is then passed through water clarifier. Water cleared by this process is called clarified water.

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

Ans- 

Semi-solid wastes such as faeces that settle down at the bottom during wastewater treatment are called sludge. Sludge is removed with a scraper. The sludge is then transferred to a separate tank where it is decomposed by the anaerobic bacteria. In this process biogas is produced.

The biogas produced can be used as a fuel or can be used to produce electricity.

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

Ans- 

Untreated human excreta is a health hazard because it pollutes soil and water. Both the surface water and ground water gets polluted. Due to contamination of ground water, various water bodies such as wells, tube wells, ponds, etc. also get contaminated as ground water is the source of water for them. When water from these contaminated sources is used for domestic purposes, it may cause several water borne diseases such as cholera, dysentery, meningitis, etc.

Q.7 Name two chemicals used to disinfect water.

Ans- 

Two chemicals used to disinfect water are chlorine and ozone.

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

Ans- 

In wastewater treatment plant bar screens are used to separate large objects like rags, plastic packets, napkins, etc. by passing water through them.

Q.9 Explain the relationship between sanitation and disease.

Ans- 

Lack of sanitation may cause diseases. Large fraction of people defaecate in open, on dry river boards, railway tracks and many times directly in water. It results in pollution of water and many diseases. Diseases like typhoid, meningitis, hepatitis, dysentery, etc. are caused due to poor sanitation.

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

Ans- 

Our role as an active citizen should be in maintaining sanitation in neighbourhood and at public places. We can limit the type of waste and quantity of waste produced. For this every citizen should follow these steps.

1. Do not drop litter. Carry the litter to home if any dustbin is not found nearby.
2. Contribute and coordinate with government plans.
3. If drains are not covered, report it to municipality.
4. If the sewage of any particular house makes the neighbourhood dirty, request them to be more considerable about others health.

 

Q.11 Here is a crossword puzzle. Good luck!


Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body

Down
1. Used water
2. A pipe carrying sewage
5. Micro-organism which causes cholera
7. A chemical to disinfect water

Ans- 

Q.12 Study the following statements about ozone:
(a) It is essential for breathing of living organisms.
(b) It is used to disinfect water.
(c) It absorbs ultraviolet rays. (d) Its proportion in air is about 3%.

Which of these statements are correct?
(i) (a), (b) and (c)
(ii) (b) and (c)
(iii) (a) and (b)
(iv) All four

Ans- 

The correct option is option (ii).

For viewing question paper please click here

FAQs (Frequently Asked Questions)
1. Why should Class 7 students refer to NCERT Solutions for Class 7 Science Chapter 18 by Extramarks?

Class 7 students should refer to NCERT Solutions for Class 7 Science Chapter 18 by Extramarks because the material is simple, detailed and reliable.  It provides a complete solution to all the subjects so that the students need not look for any other coaching class or resource for additional help. It’s a one stop solution for all your problems, irrespective of your level  NCERT solutions can make a difference in your performance within a short span of time.   There are other reasons which can’t be overlooked: 

  • It is curated by experts in a simplistic manner. This enables students to quickly understand even the most complex concepts. 
  • NCERT Solutions for Class 7 Science Chapter 18 by Extramarks are prepared as per the latest CBSE guidelines.
  • NCERT Solutions for Class 7 Science Chapter 18 can be accessed on the Extramarks’ website or app.

2. How to score high marks in Science?

Here are a few tips to score high marks in NCERT Class 7 Science Chapter 18:

  • Refer to a reliable study material like NCERT Solutions for Class 7 Science Chapter 18 by Extramarks.
  • Always go through  the chapter the same day it is taught in school. Do not wait until exam time to master the topic..
  • While studying,  take notes of complex topics. Always write pointwise.  . When preparing for tests and exams  give extra attention to it  
  • Do not forget to practise diagrams, if any. 
  • Always understand the concepts instead of learning by heart.

3. Is NCERT Science Class 7 Chapter 18 important?

Absolutely!  NCERT Science Class 7 Chapter 18 is important. And no, we don’t mean the chapter is important only from an examination point of view. It is important to provide students with experiential learning since water is an important resource whether it’s  pure water or wastewater.  This chapter focuses on  wastewater which contains elements  toxic to humans and the ecosystem. The treatment  of wastewater can purify  water supply and protect the planet from toxins.  A student will learn everything about water, how precious it is and why it is so necessary to conserve it. When a student learns this at such a young age, the student will become a better citizen taking care of its environment in every possible manner and work towards safeguarding the ambience and not polluting it.

4. Does Extramarks provide any other material other than NCERT Solutions?

Extramarks is a kind of repository and has an abundance of resources.. Be it NCERT Solutions, practise exercises, MCQs, question banks, past year’s questions papers, or frequently asked questions, all learning materials are available on the Extramarks’ website. 

5. Give an overview of NCERT Science Class 7 Chapter 18.

NCERT Science Class 7 Chapter 18 covers many interesting topics. Firstly, it gives students a thorough understanding of wastewater. It throws light on what happens to the water after we use it and after it goes down the drain. It explores  subjects like treatment of water, sewage, and how untreated human excreta can be a health hazard for us. This is an important chapter because it gives you knowledge about  different types of wastewater and how it impacts the environment and our daily life and its treatment.