CBSE Class 8 Science Pollution Of Air And Water Worksheet Set A

A. Multiple Choice Questions-

Question. Which gas can kill a person, when inhaled in excess?
a. carbon dioxide
b. carbonmonoxide
c. oxygen
d. sulphur dioxide
Answers. (b) carbon monoxide

Question. The problem by the inhalation of dust particles of air is_____
a. irritation of eyes
b. Respiratory problem
c. bronchitis
d. brain damage
Answers. (c) bronchitis

Question. Ultraviolet radiation coming from the sun are stopped by an atmospheric layer rich in______
a. ozone
b. oxygen
c. nitrogen
d. hydrogen
Answers. (a) ozone

Question. Ozone hole is found right above______
a. Africa
b. Asia
c. Antarctica
d. Australia
Answers. (c) Antarctica

Question. Increasing percentage of carbon dioxide leads to_______
a. deforestation
b. global warming
c. floods
d. suffocation
Answers. (b) global warming

Question. Which of the following is not a cleaner source of energy?
a. fossil fuels
b. hydroelectricity
c. solar energy
d. wind energy
Answers. (a) fossil fuel

B.Fill in the blanks-
1. The increase in concentrate of _______causes global warming.
2. ________ used in refrigerators ,damage the ozone layer of the atmosphere.
3. Water that is suitable for drinking is called ______ water.
4. Water is allowed to stand for a day in ______ tank in water treatment plant.
5.Taj Mahal is highly affected by _____ pollution.
Answers.
1.carbon dioxide
2.chlorofluorocarbons
3.potable
4.sedimentation
5. air

C. Very Short Question-

Question. What is the loss of dissolved oxygen from water in water bodies called?
Answers. The loss of dissolved oxygen from water in water bodies is called eutrophication.

Question. Name a cleaner source of energy for producing electricity.
Answers. Wind energy

Question. What causes acid rain?
Answers. When harmful gases like sulphur dioxide and nitrogen dioxide , 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.This is called acid rain.

Question. Name the compound added in loading tank to purify water.
Answers. Alum is the compound added in loading tank to purify water.

Question. When was the Ganga Action Plan launched?
Answers. The Ganga Action Plan was a programme launched by the Government of India in April ,1985, in order to reduce the pollution level in the river.

Question. Name two air pollutants and their sources.
Answers. The two air pollutants and their sources are-
1.Smoke. Incomplete combustion of fossil fuels
2. Chlorofluorocarbons. Used in refrigerators, air conditioner and sprays cans

D. Short Questions-

Question. What is global warming?
Answers. Global warming is the rise in average temperature of the atmosphere of the earth due to increase in greenhouse effect.

Question. Give any two methods to control air pollution.
Answers. The two methods to control air pollution are-
1.We can plant trees to reduce the level of carbon dioxide and air pollution.
2. By using CNG and unleaded petrol in our vehicle.

Question. Define (a) algal bloom (b) eutrophication.
Answers. (a) Washing away of fertilisers into water bodies causes increased growth of agar and other weeds in water indies. This is called algal blood.
(b). The process of nutrient enrichment of water bodies that stimulates the growth of aquatic plants like algae that may result in depletion of dissolved oxygen is called eutrophication.

Question. What are the natural sources of air pollution?
Answers. The natural sources of air pollution are forest fires, volcanic eruption, wind erosion,pollen dispersal and evaporation of organic compound.

Question. List two ways of reducing water pollution.
Answers. (a) Excessive use of fertilisers and pesticides should be discouraged.
(b) Pollution control rules enforced by the government should be followed strictly.

Question. What is biological magnification?
Answers. The increase in concentration of harmful chemicals substances like pesticides in the body of organisms at each trophic level of a food chain is called biological magnification.

Question. What are the damaging effects of ozone layer depletion?
Answers. Damaging effects of ozone layer depletion-
a. Harmful ultraviolet radiations reaching the earth cause various diseases in human such as cataract, skin cancer etc.
b. It can bring about changes in the gene structure leading to mutations.
c. It causes damage to early developmental stages of fishes,crabs and other animals.

Question. What are the two causes of water pollution?
Answers. The two cause of water pollution are-
a. Industrial sewage – Industries of paper , textile, sugar mills etc. discharge untreated industrial sewage directly into the water bodies which causes water pollution.
b. Human activities- Bathing of human beings and animals in or near lakes, rivers etc pollutes the water bodies.

Question. Discuss the damaging effects of acid rain .
Answers. Damaging effects of acid rain-
a. Acid rain increases the acidity of soil and thus ,affects the plants and animal life. It leads to the loss of soil fertility.
b. It makes lakes and rivers water acidic leading to destruction of aquatic plants and animals.
c. Acid rain destroys monuments and buildings.

E. Long Questions-

Question. (a) What is green house effect ? Name two greenhouse gases.
(b) Discuss the harmful effects of global warming.
Answers. (a) The phenomenon whereby the earth’s atmosphere traps solar radiation because of the presence of gases like carbon dioxide,nitrous oxide ,water vapour ,methane and CFCs is called greenhouse effect.
(b). Damaging effects of global warming –
1. Polar ice caps would melt and water would flow into the sea. If the level of water in the sea increase, low lying areas near coasts would be submerged.
2. Climate and rainfall pattern would change.
3. It would also affect agriculture and thus production of food.

Question. Briefly discuss the steps involved in purification of river or lake water.
Answers. Before water reaches our homes, it needs to be cleaned by removing the impurities and kill disease causing microorganisms. Water is cleaned in the water treatment plant consisting of different tanks. Water from river or lakes is first pumped into the sedimentation tank.
1.Sedimentation tank:- Water is allowed to stand for a day. Most of the large insoluble impurities settle down at the bottom of the tank. Some light soluble impurities remain suspended in water.
2. Loading tank:- Water is passed into loading tank. The suspended impurities are made to settle down faster by the addition of some chemicals like alum. This is called loading.
3. Filtration tank:- The water is then passed to filtration tank. Here, water passes through the layers of sand, gravel and charcoal that filter the remaining lighter suspended impurities.
4. Chlorination tank:- The water is then passed into the chlorination tank. Here, chlorine is added to the water. lt kills all the disease causing microorganisms present in the water.
5. Storage tank:- After purification, the safe drinking water is collected in big storage tanks. From these tanks, it reaches our homes through pipes.

More Question

Q.1 Fill in the blanks:-

(i) By volume about _______ of air is nitrogen and about _________ is oxygen.
(ii) Incomplete burning of fuels produces ________ which is a _______ gas.
(iii) Carbon monoxide _________ the oxygen carrying capacity of the blood.
(iv) Petroleum refineries are a major source of gaseous pollutants like ______ and ______.
(v) _______ used in refrigerators damages the ozone layer of the atmosphere.
(vi) Ozone layer protects us from the harmful ________ rays of the sun.
(vii) _______ of the world’s population is without safe drinking water.
(viii) We can save water by remembering the 3R’s ____, ____ and ________.
(ix) Acid rain is formed by the oxidation followed by dissolution of ________ and gases in rain water.

Q.2 MULTIPLE CHOISE QUESTIONS: (Choose the most appropriate answer.?

(A) Which of these causes water pollution?
(a) Sewage
(b) Industrial waste
(c) Fertilizers and pesticides
(d) All of these

(B) Which of these processes can not remove germs from water?
(a) boiling
(b) Filtration through Porous Pot
(c) Reverse Osmosis
(d) exposure to UV light

(C) Which of the following is not a pollutant unless present in excess?
(a) Sulpher Dioxide
(b) Carbon dioxide
(c) Nitrogen dioxide
(d) carbon monoxide

(D) Which of these can cause acid rain?
(a) Sulpher Dioxide
(b) Carbon dioxide
(c) Nitrogen
(d) carbon monoxide

Q.3 Define air pollution. What are air pollutants?

Q.4 What are the various sources of air pollutants?

Q.5 What is smog? Why is it harmful?

Q.6 What is acid rain?

Q.7 How is the Taj Mahal affected by air pollution?

Q.8 What is meant by ‘Marble Cancer’?

Q.9 Write the full forms (i) CFC (ii) CNG (iii) LPG (iv) WWF

Q.10 What is greenhouse effect? Name four greenhouse gases.

Q.11 Write a note on global warming mentioning its effects too.

Students must free download and practice these worksheets to gain more marks in exams. CBSE Class 8 Science Worksheet - Pollution of Air and Water Part B