DAV Class 8 Science Chapter 20 Solutions Pollution of Water of The Living World Science Book guides you with the answers to the questions given in the textbook. Class 8 is an important phase of the student’s life as they are introduced to many new concepts that are essential to set strong basics foundation for the topics to be taught in Class 9.
This chapter deals with water pollution. In class seven, we learnt that water is a precious resource. We also learnt about the scarcity of water and its causes. Water pollution is one of the most common topics that are repeatedly asked in the class 8 examination.
Dav Class 8 Science Chapter 20 Pollution of Water Question Answer
DAV Class 8 Science chapter 20 question answer Pollution of Water, is given below. Here DAV Class 8 Science Chapter 20 solutions is provided with great explanation. To help DAV Class 8 students clear their doubts instantly, Class 8 Science Chapter 20 question answer Pollution of Water come as a great resource.
- Fill in the blanks
- State True or False
- Tick the correct option
- Answer the following questions in brief
- Answer the following questions
These DAV Class 8 Science Chapter 20 Pollution of Water Solutions will help you in scoring good marks as they cover important concepts in different patterns like fill in the blanks, tick the correct option, State True or False for the following statements, Answer the following questions in brief and Answer the following questions.
DAV Class 8 Science Chapter 20 Solutions
1. ___________ is a chemical method of purifying water.
2. ___________ and ___________ constitute agricultural wastes.
3. The presence of domestic sewage, in water, promotes the growth of ___________ and ___________ which use up a lot of oxygen, present in water.
4. Water, that is safe for drinking, is called ___________ water.
5. One of the purposes of purification of water is to remove the ___________ impurities, present in it.
Answer: (1) Chlorination (2) Fertilizers, pesticides (3) algae, bacteria (4) potable (5) suspended.
1. A bad taste of water indicates the presence of pollutants in it.
2. We should always bathe, and wash clothes, in rivers.
3. Potable water can cause water borne diseases.
4. We should always wash and clean our vehicles with tap water using a pipe.
5. The ‘waste water’ produced by the industrial units, must be (appropriately) treated before it is discharged into rivers.
Answer: (1) True (2) False (3) False (4) False (5) True.
1. Domestic sewage, released into rivers, causes-
Answer: growth of algae
2. Water, which is safe for drinking, is known as-
Answer: potable water
3. One of the methods, that can help in destroying harmful germs in water, is-
4. Suspended particles are made heavier by adding alum. This process is known as-
5. A method, that can help in conservation of water, is-
Answer: half flush
1. State any two ways which can lead to contamination of water.
Answer: two ways which can lead to contamination of water are:
- Industrial wastes contaminate water to a large extent.
- Human activities, like bathing and washing of clothes, in rivers and ponds, can contaminate the water.
2. Give the meaning of the term ‘water pollutants’.
Answer: Any foreign materials, that pollute water, act as water pollutants.
3. Name two of the main diseases that can be caused by drinking contaminated water.
Answer: Jaundice and diarrhoea are the diseases that can be caused by drinking contaminated water.
4. Name two chemicals that may help in purifying water.
Answer: Alum and chlorine (bleaching powder) are two chemicals that may help in purifying water.
5. Name the kind of ‘growths’ in water that lead to a depletion of the oxygen dissolved in it.
Answer: Growth of algae and bacteria.
1. List the main parameters that need to be followed before water is supplied for drinking purposes.
Answer: The following parameters need to be followed before water is supplied for drinking purposes are:
- It must be colourless and free from any odour or smell.
- It must be free from suspended impurities.
- It should be tasteless.
- It must be free from microorganisms which lead to many diseases.
- It must be free from harmful chemicals.
2. Write, in brief, (i) one physical and (ii) one chemical method that can be used for ‘water purification’.
Answer: (i) Physical method for ‘water purification’:
Filteration: Water can be purified by passing it through layers of sand, gravel and charcoal, one by one. This is a physical method of removing impurities. This has been, and can still be, the method that may be used in the absence of alternative and more advanced methods.
(ii) Chemical method for ‘water purification’:
Chlorination: This is a chemical method for purifying water. It is done by adding chlorine tablets (or bleaching powder) to water. This is a method that needs to be used with care. We should not use more chlorine tablets than specified.
3. State the measures that must be taken to check water pollution by sewage.
Answer: Following measures must be taken to check pollution by sewage:
- Sewage must be churned by machines.
- Treatment of water with alum also helps in its purification.
- Water must be sterilised by chlorination. It kills the microbes.
4. Suggest some simple steps that can be taken to help in conserving water.
Answer: These are some simple steps that can be taken to help in conserving water:
- Immediately repair any leaking tap in the home.
- Do not leave the tap open while brushing your teeth.
- Do not wash your car with tap water using a pipe.
- Do not leave the water ‘running’ when washing dishes by hand.
- Avoid using shower; it is better to use a bucket and mug for taking bath.