DAV Class 8 Science Solution Chapter 20 Pollution of Water
DAV School Books Class 8 Science Solution Chapter 20 Pollution of Water all Question Answer. DAV Class 8 20th Chapter Pollution of Water full Chapter explanation by expert teacher.
DAV School Books Class 8 Science Solution Chapter 20 Pollution of Water
A.) Fill in the blanks.
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.
B.) State True or False for the following statements.
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, we should wash clothes at home with only a certain amount of water (3) False, impure water can cause water borne diseases (4) False, we should clean them by using water from a bucket (5) True.
C.) Tick the correct option.
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-
Answer: chlorination
4.) Suspended particles are made heavier by adding alum. This process is known as-
Answer: loading
5.) A method, that can help in conservation of water, is-
Answer: half flush
D.) Answer the following questions in brief.
1.) State any two ways which can lead to contamination of water.
Answer: The ways are as follows:
Pollution: Pollution is one of the most frequent ways that water can get contaminated. This can include sewage, agricultural runoff, and industrial waste, all of which may carry dangerous diseases and chemicals.
Oil Spills: Another method that waterways can be contaminated is by oil spills. When a significant volume of oil is unintentionally released into a water body such as a sea or river, it causes an oil spill. Fish, birds, and other species may become suffocated and their homes harmed by the oil, which can cover the the water’s surface and its surroundings.
2.) Give the meaning of the term ‘water pollutants’.
Answer: Any substance that destroys the quality of water, aquatic life is known as water pollutant.
3.) Name two of the main diseases that can be caused by drinking contaminated water.
Answer: Cholera and Typhoid are two disease that occur from having contaminated water.
4.) Name two chemicals that may help in purifying water.
Answer: potash/alum and chlorine are utilised to purify water.
5.) Name the kind of ‘growths’ in water that lead to a depletion of the oxygen dissolved in it.
Answer: Algae blooms are a type of aquatic development that causes dissolved oxygen levels to drop. Algae blooms are overgrowths of algae in a pool of water that can harm aquatic life and reduce oxygen levels.
E.) Answer the following questions.
1.) List the main parameters that need to be followed before water is supplied for drinking purposes.
Answer: The following parameters should be met in order for water to be drinkable:
- The water should not taste or smell unpleasant.
- The water has to be colourless, transparent, and clear of any particles.
- It is crucial to make sure that the water is clear of dangerous microbes because germs, infections, as well as other microorganisms can lead to diseases and illnesses.
- There should be no dangerous chemicals in the water.
2.) Write, in brief, (i) one physical and (ii) one chemical method that can be used for ‘water purification’.
Answer: The following methods can be used:
- Filtration (physical): In order to clean the water, this process uses the physical boundary, like a filter. Sand, pebbles, or filter paper are examples of materials that can be used to make the filter.
- Chlorination (chemical): In order to eliminate dangerous germs from the water, this technique uses chlorine as well as other disinfectants. Usually, a tiny amount of chlorine is added to the water during treatment to destroy bacteria, viruses, as well as other diseases.
3.) State the measures that must be taken to check water pollution by sewage.
Answer: Sewage contamination of water can have negative effects on the ecosystem and human health. Several actions can be made to regulate and stop sewage pollution. Sewage treatment and disposal is among the most crucial procedures. This can be accomplished by using treatment facilities that filter out contaminants and dangerous microorganisms from sewage before releasing it into freshwater bodies of water. In order to avoid spills and leaks, it’s also critical to maintain as well as repair the sewage system.
4.) Suggest some simple steps that can be taken to help in conserving water.
Answer: The following methods can be used to conserve water:
- Gather rainwater inside a container and use it to irrigate plants.
- To water the garden, use a watering bucket rather than a pipe.
- Use only normal load in the laundry and wash basin.