Pollution of air and water Class 8 Extra Questions- Chapter 18

(i)Eutrophication is a condition in which water becomes rich in nutrients that leads to the growth of unwanted plants.
(ii)Water pollution is a harmful condition which makes water contaminated due to the addition of fatal substances (water pollutants) in it.
(iii)Power plants and factories use water bodies as coolant. As a result, the hot water transfers to these water bodies that increases the temperature and reduces the amount of oxygen. This condition is known as thermal pollution.
(iv)Chlorination is a process of killing germs by adding liquid chlorine or sodium hypochlorite.
(v)Potable water is a fresh water that is used for drinking.  

a. IV
b. I
c. II
d. V
e. III

The Indian Government encourages people to not use charcoal and wood for cooking because these materials release carbon monoxide, carbon dioxide and suspended particulate matter when they burn. All these released compounds that are harmful for us although they pollute the air tremendously.

The environmentalist explained this statement scientifically by mentioning the facts that the oil spills in the water bodies lead to the water pollution that harms the life of marine animals and plants. In addition, it also increases the difficulty for using these water bodies for other purposes. Therefore, ships need to design in such a way that their oil can’t spill in the water bodies.

Industrial emission has become the second leading cause of air pollution because using charcoal as a main source of fuel for producing energy and other products release the harmful gases like sulphur dioxide, carbon dioxide, smoke and dust. All these released materials are air pollutants.

Smog is a combination of smoke and fog. It reduces the visibility and forms a layer in the atmosphere called haze. Smog decreases the amount of oxygen which causes shortness of breath, chest pain, wheezing and coughing. It also provides a suitable condition of various dangerous pathogens that are responsible for causing emphysema, bronchitis and asthma.

Burning of fossil fuels produces sulphur dioxide and nitrogen oxides involve with the water vapours in the atmosphere. As a result, the rain is highly acidic due to oxides which are highly acidic.

The project “Save Taj” launched in 1983 because the white marble of “The Taj Mahal” were damaged due to the extreme climatic conditions. This project was launched to repair the damage.

The following three steps to prevent water pollution are: -
(i)Do not wash clothes near the water bodies.
(ii)Do not throw waste products in the water bodies.
(iii)Instead of chemical fertilisers and inorganic pesticides, biofertilisers and biopesticides should be considered.

The following three steps to prevent air pollution are: -
Using alternative sources of energy like wind and solar energy should reduce the air pollution.
Using air filters for cleaning air.
Establishing factories and industries away from the cities.

The following steps explain the process of water purification for public distribution are: -
(a)A large amount of water is collected from the water bodies that passes through the screen filters which clear the impurities like leaves, pebbles, twig and waste products. Afterwards, this water is transported to a water treatment plant for purification.
(b)At the water treatment plant, muddy water is collected in large tanks for a long period of time. This process helps to settle down the impurities at the bottom of the tanks. Afterwards, alum is added to remove the additional impurities. Later, this clear water is transferred for filtration.
(c)In filtration, charcoal is used to remove the colouring matter and sand collects the suspended impurities. Afterwards, chlorination takes place.
(d)Now, liquid chlorine or chlorine compounds like sodium hypochlorite and bleaching powders are added in a sufficient amount in the filtered water to kill germs.
(e) This chlorinated water is now tested in water laboratories. After the verification of water purity, this water supplies into the public water supply.

The following causes of air pollution is given below: -
Automobile Emissions: These emissions are the largest cause of air pollution because the vehicles on the road release smoke that contains harmful air pollutants like carbon monoxide, carbon dioxide and lead.
Industrial Emissions: These emissions are second largest cause of air pollution. The establishment of industries and factories produce goods in a large scale. Therefore, they require a large number of raw materials for the production. They use coal as a main fuel. As a result, burning of coal releases harmful compounds such as sulphur oxide, carbon monoxide and carbon dioxide.
Suspended Particulate Matter: They are the main source of haze. There are numerous suspended particulate matters present in the air in the form of dust and smoke. These can become more fatal as they suspended in the air for a long period of time because they can increase the rate of respiratory disorders among people. There are two types of suspended particulate matter- Coarse and fine particles. Coarse particles are the released particles from the vehicles while fine particles are released from the burning fossil fuels.
Some of fatal air pollutants are carbon monoxide, carbon dioxide, chlorofluorocarbons and sulphur oxide. All these air pollutants effect the environmental condition severely. This leads to extreme condition for surviving.
Some of the other causes are burning charcoal and wood. Some agriculture practices also pollute the air.