RBSE Class 8 Science Chapter 16 Air and Water Pollution and its Control Textbook Solutions

In RBSE Class 8 Science Chapter 16 Air and Water Pollution and its Control, students learn the causes of water and air pollution and some corrective measures to keep it under control. In this article, we bring you the important questions and solutions of this chapter that will help students to grasp an in-depth understanding of all important topics included in this chapter and excel it thoroughly.

Our subject matter experts have designed the solutions in a simple manner and covered all the key explanations of important questions of different chapters in the RBSE Class 8 Science syllabus. We hope that students can benefit from these readily available solutions and discover new concepts, and it will help them while prepping up for the RBSE Class 8 2020 exam.

Along with the exercise and textbook questions, there are some solved additional questions with solutions of the RBSE Class 8 Science for Chapter 16 Air and Water Pollution and its Control from the RBSE Class 8 Science Syllabus. Students can check this out and practice from these questions to have a thorough knowledge of the chapter and revise from these solutions before their exams and score high marks in this subject.

Rajasthan Board Class 8 Science Chapter 16: BYJU’S Important Questions & Answers

RBSE Class 8 Science Chapter 16 Objective Questions: Textbook Important Questions and Solutions

Multiple Choice Questions (MCQs)

Mark the correct option:

Question 1: Which of the following is not a greenhouse gas?

(a) Carbon dioxide

(b) Sulphur dioxide

(c) Methane

(d) Nitrogen

Answer: (b) Sulphur dioxide

Question 2: Which of the following is a poisonous gas?

(a) Carbon monoxide

(b) Hydrogen

(c) Oxygen

(d) Nitrogen

Answer: (a) Carbon monoxide

Question 3: It is used in the refrigerators:

(a) Hydrogen

(b) ChlorofluoroCarbon

(c) Nitrogen

(d) Oxygen

Answer: (b) ChlorofluoroCarbon

Question 4: Holy river of India is:

(a) Ganga

(b) Bedach

(c) Banas

(d) Kosi

Answer: (a) Ganga

Fill in the blanks:

Question 5: The substances that pollute the water are called ______________ .

Answer: pollutants

Question 6: The average temperature of the atmosphere is continuously increasing. This is called _____________________ .

Answer: global warming

Question 7: ______________ is used in aerosol sprays.

Answer: CFC

Question 8: Clean drinking water is called _______________________ .

Answer: potable water

Match column A and B:

Answers:

Short Type Answer Textbook Questions

Question 1: Mention the harmful effects of air pollution.

Answer: Some of the harmful effects of air pollution include:

1. Due to incomplete combustion of diesel and petrol, a poisonous gas – carbon monoxide (CO) is produced which decreases the oxygen carrying capacity of blood.

2. Tetraethyl lead is a dangerous pollutant which is present in petrol and one of the major causes of cancer and tuberculosis.

3. During winters, a thick layer of smog is formed in the atmosphere due to smoke and fog, collectively known as smog. It contains nitrogen oxide which causes severe respiratory problems such as asthma, cough, bronchitis, etc.

4. Poisonous pollutants such as nitrogen oxide and sulphur dioxide are released from petroleum refineries. These are used in electrical appliances and cause lung-related disorders.

5. Chlorofluorocarbon (CFC) is an air pollutant that is used in refrigerators, aerosol sprays and air conditioners. It affects the ozone layer of the atmosphere which protects us from dangerous ultraviolet rays of the sun. Excess dissolution of CFC in the atmosphere is gradually causing a hole in the ozone layer which might lead to an acute problem in the near future.

6. Industries and factories emit poisonous gases such as sulphur dioxide, chlorine, nitrous oxide, etc. causing an acute burning sensation in our eyes and throat and causes severe ailments.

7. Aluminium and Super phosphate factories also produce poisonous gases which cause many severe health problems.

8. Air pollution causes severe damage to plants too and sulphur dioxide emission in the air also results in death of plants.

Question 2: What is global warming?

Answer: Excess of carbon dioxide in the atmosphere is a major air pollutant. It prevents the excess heat caused by sun rays from escaping out of the atmosphere. This causes a continuous increase in the average atmospheric temperature. This is known as global warming.

Question 3: What is acid rain? How does it affect us?

Answer: When nitrogen, sulphur and carbon dioxides react with water, they form nitric acid, sulphuric and sulphurous acid and carbonic acid. These have a damaging effect in the environment and form acid rain. They make the rain water acidic in nature and fall on earth along with the rain. Acid rain causes major degradation of historical monuments and causes Marble cancer. Apart from affecting buildings, railway lines, etc. it affects pond water and makes it acidic too. pH level of the soil decreases and this affects the absorption of minerals by the plants from soil causing it to become infertile. Further, acid rain also causes burning sensation in eyes and skin and ruins the membranes of plants and animals.

Some of the measures taken by the Supreme Court to conserve historical monuments include:

1. Strict instructions are given to industries to use bio-fuels such as Compressed Natural Gas (CNG) and Liquified Petroleum Gas (LPG).

2. Instructions were given to located residents in Agra to use lead free petrol in motor vehicles plying near the Taj Mahal area.

Question 4: Write the methods to prevent air pollution.

Answer: Some of the steps for air pollution control include:

1. There should be gas absorbers on chimneys of all industries.

2. Use of filters is a must to separate out pollutant particles.

3. Combustion engines should be checked on a regular basis.

4. Ideal fuels should be used so there is less smoke and emission of harmful gases can be minimized.

5. Waste gases and smoke should be oxidised, so that would help in reducing pollution.

6. Industries should be established and located far away from the residential areas in the cities.

7. There should be a ban in deforestation.

8. Plantation process should be expedited.

9. Public awareness programmes should be conducted to maintain environmental cleanliness.

10. Lead free petrol, CNG and LPG should be used in motor vehicles.

11. There should be a ban in use of crackers during Diwali to decrease pollution.

12. Government should monitor the air quality regularly.

13. Wind energy, solar energy and hydro power should be used as alternative fuels of energy.

14. Millions of plants should be planted in July month as a part of Van Mahotsav.

15. Less vehicles should be used.

16. Use of bicycles should be encouraged among people.

16. Garbage should be dumped into the compost pit.

Question 5: What is the greenhouse effect? Write its effect.

Answer: The earth’s atmosphere is like a greenhouse. When the sun rays reach the earth’s atmosphere, it heats the earth’s surface. Some solar radiations are absorbed by the earth and some are reflected back to outer space. These radiations which stay back tend to heat up the environment. This effect is known as the greenhouse effect. In this scenario, carbon dioxide increases in the atmosphere which acts like a pollutant. Carbon dioxide absorbs the heat and prevents it from escaping the environment. It has severe impacts on the agriculture, flora and fauna and as the temperature continues to rise, various countries are making efforts to decrease the amount of emission of poisonous greenhouse gases, such as methane, nitrous oxide and water vapour.

Question 6: What are air pollutants?

Answer: Substances which cause major environmental disruption and degradation are known as pollutants such as carbon dioxide, nitrogen oxide, carbon monoxide that is present in the smoke emitted out of automobiles, etc.

Long Type Answer Textbook Questions

Question 7: What is water pollution? What are the harms caused by water pollution? Write the methods to prevent water pollution.

Answer: Water Pollution: The contamination of water with harmful substances that degrades the quality of water and affects its taste and colour is known as water pollution.

Causes of water pollution:

(a) Water gets polluted when various garbage, industrial waste, polythene and other waste mix in the water bodies.

(b) Dirty drain water in rural areas mix with rivers and ponds.

(c) Washing clothes and utensils, bathing, dumping garbage in water, bathing animals in rivers or ponds, disposing solid and liquid waste, cleaning vehicles in rivers or ponds pollute the water.

(d) Use of pesticides and chemical fertilizers for expediting the growth of crops get mixed in the soil and reach rivers along with rain water, thereby causing water pollution.

(e) Ocean water also gets polluted with the dumping of waste oils, atomic tests and radiations of these explosions.

Effect of water pollution:

When solid waste is dumped in water, it pollutes the water. This polluted water contains various microbes, algae, fungi, parasites etc. Such polluted water can cause severe skin infections and diseases like cholera, typhoid, diarrhoea, etc. Polluted water also reduces the oxygen supply to aquatic animals and plants and has an adverse effect on their growth and development. Due to this reason, their number is seeing a sharp decline and makes the soil polluted and decreases its fertility. Paper industries, oil refineries and sugar industries also emit poisonous gases such as lead, arsenic, fluoride, etc. Hot water expulsion from factories and electric plants also increases the temperature of ponds and impacts the aquatic ecosystem. Use of pesticides and fertilizers also get mixed with the soil and dissolve in water and reach the underground water causing water pollution.

Measures to control water pollution:

(a) Industrial waste from the industries should not be dumped in water bodies.

(b) According to the Government laws, industrial wastes should be treated properly and then discharged in water. These laws need to be followed strictly.

(c) Atomic explosions should be banned in seas and oceans.

(d) Bathing of animals,washing clothes and utensils in rivers should be avoided.

(e) Solid and liquid waste should not be disposed of near rivers banks or ponds.

(f) Proper and clean water supply sources should be ensured regularly.

(g) Domestic waste should be disposed of at the right place such as compost pits.

(h) There should be proper water purifier

plants installed in every city and tehsil level so that pollutants from water can be effectively treated and removed.

Question 8: Write in detail about the danger over river Ganga.

Answer: Ganga is considered the holiest river among all famous rivers of India. It is also popularly known as “Ganga Mata”. Ganga water remains pure and clean if kept for many days. It nourishes the population of East and North India. According to the study conducted by the World WildLife Federation (WWF), Ganga is one among the ten rivers of the world whose existence is in extreme danger. Due to the substantial growth in population and industrialization, people living in the cities and villages dump unnecessary garbage chemical wates, dead bodies of animals, immerse idols, throw flowers, pooja essentials and polythene directly into this river. Due to this reason, Ganga or the Ganges is getting polluted day by day.

In 1985, to save this river, Ganga River Plan was started but booming population and industrialization have had an extreme toll and incurred severe harm to this river. At present, the Government of India has started a unified plan ‘Namami Ganga’ for the conservation of this river. However, all Government departments and people should cooperate to make the programme a super success.

Additional Short Type Answer Questions

Question 1: Define air pollution.

Answer: Air pollution is the quantitative and qualitative change in the general composition of air. It is the contamination of air that we breathe with poisonous gases such as methane, nitrous oxide, etc. Such pollution is caused by the emission of dangerous gases by automobiles, industries, mining factories, volcanic eruptions, forest fires, etc. All these collectively have an impact on the environment and cause air pollution and release impure dust particles and smoke in the atmosphere.

Question 2: Mention two characteristics of Chlorofluorocarbons (CFCs).

Answer: Given below are the two characteristics of Chlorofluorocarbons (CFCs):

1. CFCs are used in air conditioners, refrigerators and aerosol sprays.

2. CFCs harm the atmospheric ozone layer and cause a hole in it.

Question 3: Explain how burning of fossil fuels causes air pollution.

Answer: Fossil fuels like petroleum, coal, etc. are rich sources of energy. When these fuels are burnt, they produce energy and carbon dioxide and other poisonous gases such as carbon monoxide, sulphur dioxide, nitrogen oxides and smoke particles. Hence, combustion of fossil fuels causes a lot of atmospheric pollution.

Question 4: Identify one harmful air pollutant which causes life-threatening disorders?

Answer: Lead petrol is one such harmful air pollutant which consists of Tetraethyl lead. It is one of the major causes of cancer, tuberculosis (T.B.) and other fatal respiratory ailments.

Question 5: Define algae-bloom. Explain its harmful effects.

Answer: Chemical wastes such as nitrates and phosphates get mixed and deposited with water bodies such as ponds and rivers. These act as nutrients for algae and to flourish tremendously. This is known as algae-bloom or algal bloom. These algae use a lot of oxygen in the water bodies due to which there is a decrease in the oxygen level which causes death of aquatic organisms.

Question 6: Name some of the major air pollutants.

Answer: Substances which pollute the air on a massive scale are regarded as air pollutants. Some of these pollutants include carbon dioxide, carbon monoxide, nitrogen oxides, etc.

Question 7: What are the gaseous pollutants used in electrical devices that cause lung disorders?

Answer: Some of the gaseous pollutants such as nitrogen dioxide and sulphur dioxide are emitted from petroleum refineries and extraction centres. The fuel is being extensively used in electrical appliances that release sulphur dioxide and cause major lung disorders.

Question 8: Name the gases released by industries that create burning sensation in the eyes and throat.

Answer: Industries and factories release poisonous gases such as sulphur dioxide, chlorine, nitrous oxide, etc. that can cause acute burning sensation in our eyes and throat and severe respiratory ailments.

Question 9: What is smog? What are its effects on the environment?

Answer: The thick layer of fog that is found in the atmosphere during the winter season is formed from a combination of smoke from vehicles and fog in the environment. In brief, it is known as smog. This smog contains nitrogen oxides which mixes with other pollutants in the atmosphere and causes severe respiratory ailments such as cough, asthma, bronchitis, etc.

Question 10: What are the fuels that cause production of carbon monoxide in the atmosphere?

Answer: Extreme combustion of fossil fuels such as diesel and petrol results in the production of a poisonous gas called carbon monoxide. It reduces the oxygen carrying capacity of blood in human beings.

Question 11: Name the different steps of water purification.

Answer: Listed below are some of the useful steps for purifying domestic and industrial water:

1. Carbon filtration

2. Boiling

3. Chlorination

4. Distillation

5. Reverse osmosis

Question 12: Identify a possible cause of global warming.

Answer: Release of poisonous greenhouse gases such as methane, nitrous oxide and water vapour in the atmosphere are a major factor which cause global warming. Due to global warming, the glaciers are melting at a rapid rate and this has caused a rise in the sea water level globally.

Question 13: What are some of the measures that the government should introduce to stop the air pollution?

Answer: There are a couple of steps that the government should introduce to reduce the effects of air pollution. These include:

1. Use of lead free petrol

2. Make usage of bio-fuels such as CNG (Compressed Natural Gas) mandatory in motor vehicles

3. Adopt usage of Euro-II standards

4. Ban on bursting crackers during Diwali

Question 14: What are the diseases caused by contamination of water?

Answer: Some of the water-borne diseases include cholera, meningitis, typhoid fever, diarrhoea, dysentery, polio, etc. Usage of unclean water for washing may also cause infectious skin and eye disease such as trachoma.

Question 15: What are the possible causes of water pollution in rural areas?

Answer: In rural areas water gets polluted due to washing of clothes and utensils, bathing tamed animals, discharging excreta in the open on river banks and ponds by the villagers.

Question 16: How does acid rain impact buildings and historical monuments?

Answer: Acid rain causes major degradation of historical monuments such as Taj Mahal and causes Marble cancer. The shine and lustre of ancient historical architecture gets greatly impacted due to the composition of nitric acid, sulphuric and sulphurous acid and carbonic acid in rain water. All these acids mix with rain water and cause acid rain. Acid rain can also cause the agricultural soil to become infertile.

Question 17: What is the impact of water pollution to aquatic life?

Answer: Due to the lack of sufficient oxygen in water bodies, there is a severe impact in the survival of various aquatic organisms such as plants and animals. This has an adverse effect on their growth and development and causes diseasing of aquatic life.

Question 18: Name one of the major chemical accidents in India which caused damage to life and property of humans.

Answer: Bhopal gas tragedy is one such major chemical accident in India which happened on 3rd December, 1984. This incident was an industrial accident which happened at a Union Carbide subsidiary pesticide plant in the city of Bhopal, India. It caused immense damage to people’s health and the environment as a whole. Thousands of people lost their lives in this tragedy.

Question 19: Describe how pesticides and fertilizers cause water pollution.

Answer: Insecticides and pesticides are extensively used by farmers to accelerate the production and growth of crops. When these chemicals get dissolved in water, they have an adverse effect on the underground water meant for drinking and pollute it.

Question 20: Explain why the chemicals expelled from industries and factories are harmful.

Answer: The chemical wastes which are expelled from the oil extraction mills, textile and sugar mills, paper industries, etc. are harmful to the environment as these contain arsenic lead and fluoride. When these chemicals get mixed with the agricultural land, they cause toxicity among living organisms.

Question 21: What is a greenhouse?

Answer: At cold places, there are some glass houses which are made in gardens and fields by farmers particularly meant to promote plant growth. These are called greenhouse. The purpose of this greenhouse is to trap the sun rays falling in these plants through the glass house and prevent the heat from escaping it. Due to this reason, greenhouses are always warm and humid.

Question 22: The increased level of nutrients in water bodies affect the survival of aquatic organisms. Explain how.

Answer: Chemicals used as pesticides and fertilizers in agricultural land dissolve in water and get washed away into water bodies from the fields. These fertilizers contain abundant quantities of chemicals like phosphates and nitrates which act as nutrients for algae to grow. When these algae die, they serve as food for decomposers. These algae use a lot of oxygen that causes reduction in the level of oxygen level that is harmful for the survival of aquatic organisms.

Question 23: How does sewage contaminate water bodies?

Answer: Sewage contaminates the water of rivers, seas and oceans as it contains various viruses, fungi, algae, bacteria and parasites. These cause various infectious diseases such as cholera, dysentery, typhoid, skin infections, etc.

Additional Long Type Answer Questions

Question 24: Describe the steps taken by the Supreme Court to save historical monuments.

Answer: Here are some of the measures taken by the Supreme Court to conserve historical heritage:

1. Strict instructions are given to industries to use bio-fuels such as Compressed Natural Gas (CNG) and Liquified Petroleum Gas (LPG).

2. Instructions were given to located residents in Agra to use lead free petrol in motor vehicles plying near the Taj Mahal area.

3. Cleaning up and discarding the discharge of chemical wastes into the Yamuna river and other rivers.

4. Establishing a green mass transit system in Agra to control pollution.

5. Promoting the sewage facility through proper treatment of plants and water bodies.

6. Establishing a rubber dam near Taj Mahal to maintain the flow of water in the Yamuna river.

Question 25: Write about Water Purification and its methods.

Answer: Water Purification: Water, which is suitable for drinking purposes is known as pure or potable water. Across the globe, about 25% of the population does not have access to clean drinking water. Impure water of water bodies should be properly treated with chemicals to make it pure and suitable for drinking purposes. Water distribution system for the public should be properly maintained and treated before supplying it to households for consumption.

Methods of Water Purification: Some of the methods to purify water are listed below –

1. Usage of domestic or candle filter.

2. Boil water before consumption.

3. Use chlorine as a highly efficient disinfectant to kill disease-causing pathogens such as bacteria, fungi, etc.

4. Use of potassium alum in raw water for filtering raw and industrial water.

5. Use or add lime and potassium permanganate in wells to make it worm-free.

We hope that the above mentioned solutions of “RBSE Class 8 Science Chapter 16 Air and Water Pollution and its Control” will help students build a strong foundation of the different concepts mentioned in the chapter.