NCERT Solutions for Class 8 Science Chapter 18 Pollution of Air and Water

Pollution of Air and Water Class 8 Questions and Answers:

Q1 . What are the different ways in which water gets contaminated?

Answer:

The different ways in which water gets contaminated are:

1. Sometimes untreated sewage is thrown directly into rivers. It contains food wastes, detergents, microorganisms, etc.
2. Many industries discharge harmful chemicals into rivers and streams, causing the pollution of water Examples are oil refineries, paper factories, textile and sugar mills, and chemical factories.
3. Pesticides and weedicides these chemicals dissolve in water and are washed into water bodies from the fields. They also seep into the ground to pollute ground water.

Pollution of Air and Water Class 8 Solutions:

Q2 . At an individual level, how can you help reduce air pollution?

Answer:

One can take these extra steps to reduce air pollution:

(i) Try traveling in public vehicles such as bus, metro, railways etc.

(ii) Try not to burn trash or any other material which would then releases harmful gases. Instead, you can dump it in the soil.

(iii) Switch to LPG or other stoves rather than cooking food in wood stoves.

(iv) Or the best is to plant a tree.

Pollution of Air and Water Class 8 NCERT Solutions:

Q3 . Clear, transparent water is always fit for drinking. Comment.

Answer:

Clear, transparent water is not always fit for drinking as it might contain some disease-causing microorganisms or other dissolves impurities or chemicals. Hence the water must have to be purified before drinking.

Class 8 Science Chapter 18 Question Answer:

Q4 . You are a member of the municipal body of your town.

Make a list of measures that would help your town to ensure the supply of clean water to all its residents.

Answer:

Measures that would help our town to ensure the supply of clean water to all its residents are:

(i) Chlorination must be done in order to purify water, also chlorine tablets or bleaching powder to the water should be added in the appropriate amount.

(ii) We check that if water that is going to supply is properly treated.

(iii) Cleaning the water tanks properly and removing layers which get deposited in walls of the tanks.

Class 8 Science Chapter 18 NCERT Solutions:

Q5 . Explain the differences between pure air and polluted air.

Answer:

Differences between Pure air and Polluted air are:

Class 8 Pollution of Air and Water NCERT Solutions:

Q6 . Explain circumstances leading to acid rain. How does acid rain affect us?

Answer:

Pollutants like sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid respectively. The acids drop down with rain, making the rain acidic. This is called acid rain.

Acid rain affects us in many ways:

(i) Acid rain corrodes the marble of the monument.

(ii) Acidic rain when flows through the soil leach out the aluminium present and flows into the rivers. It is harmful to aquatic animals.

(iii) Acid rain also removes minerals and nutrients from the soil that trees need to grow.

Class 8 Science Ch 18 Question Answer:

Q7 . Which of the following is not a greenhouse gas?

(a) Carbon dioxide

(b) Sulphur dioxide

(c) Methane

(d) Nitrogen

Answer:

(d) Nitrogen is not a greenhouse gas.

Class 8 Science Chapter 18 Solutions:

Q8 . Describe the 'Green House Effect' in your own words.

Answer:

The trapping of radiations by the earth's atmosphere is known as the greenhouse effect. Without this process, life would not have been possible on earth. Life is now threatened because of an excess of CO2 in the air and is one of the gases responsible for this effect. Some greenhouse gases are carbon dioxide, sulphur dioxide, etc.

NCERT Solutions for Class 8 Science Chapter 18:

Q9 . Prepare a brief speech on global warming. You have to deliver the speech in your class.

Answer:

Greenhouse gases like carbon dioxide, methane, nitrous oxide trap heat and do not allow it to escape into space. As a result, the average temperature of the earth’s atmosphere is gradually increasing. This is called global warming.

Deforestation leads to an increase in the amount of carbon dioxide in the air because the number of trees that consume carbon dioxide is reduced. Human activities, thus, contribute to the accumulation of carbon dioxide in the atmosphere.

Global warming is a serious threat: causing sea levels to rise in many coastal areas, also result in wide-ranging effects on rainfall patterns, agriculture, forests, plants, and animals.

Class 8 Science Chapter 18 Question Answer:

Q10 . Describe the threat to the beauty of the Taj Mahal.

Answer:

The industries located in and around Agra have been responsible for producing pollutants like sulfur dioxide and nitrogen dioxide. These gases react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. The acids drop down with rain, making the rain acidic. Acid rain corrodes the marble of the monument. The phenomenon is also called “ Marble cancer ”. Suspended particulate matter, such as the soot particles emitted by an oil refinery, has contributed towards the yellowing of the marble.

The Supreme Court has taken several steps to save the Taj. It has ordered industries to switch to cleaner fuels like CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas). Moreover, the automobiles should switch over to unleaded petrol in the Taj zone.

Pollution of Air and Water Class 8 question answer:

Q11 . Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

Answer:

The increased level of nutrients in the water affects the survival of aquatic organisms because there is an increase in the algae formation, which when dies to form as food for the decomposers and it takes a lot of oxygen from the water hence decreasing the dissolved oxygen in the water. This may affect the aquatic animals as they take in dissolved oxygen.