Chapter 18 Pollution of Air and Water mcqs & important questions science | class 8th

MCQ Questions for Class 8 Science: Ch 18 Pollution of Air and Water

1. The increase in concentration of which gas is not responsible for Global Warming?

(a) Sulphur dioxide

(b) Nitrogen

(c) Carbon dioxide

(d) Methane

► (b) Nitrogen

2. Last stage in treatment of sewage is

(a) Sterilization

(b) Evaporate

(c) Chlorination

(d) Aeration

► (c) Chlorination

3. Identify the gas associated with greenhouse effect.

(a) Carbon dioxide

(b) Oxygen

(c) Nitrogen dioxide

(d) Sulphur dioxide

► (a) Carbon dioxide

4. Which of the following is not a green house gas?

(a) Water vapour

(b) Nitrogen gas

(c) Methane gas

(d) Carbon dioxide

► (b) Nitrogen gas

5. Sea water is unfit for drinking because it contains

(a) Dead plants and animals

(b) Dissolved organic matter

(c) Rain water

(d) Large amount of salt

► (d) Large amount of salt

6. Which one is not an organic waste?

(a) DDT

(b) Paper

(c) Cotton cloths

(d) Vegetable peels

► (a) DDT

7. CNG is a

(a) polluted fuel

(b) pollution free fuel

(c) harmful fuel

(d) None

► (b) pollution free fuel

8. Most polluted river in the world is:

(a) Yamuna

(b) Cavery

(c) Chenab

(d) Ganga

► (d) Ganga

9. Addition of harmful substance in water to make it unfit for human consumption is called

(a) Water pollution

(b) Biomagnifications

(c) Decomposition

(d) Retardation

► (a) Water pollution

10. Trees help in reducing the pollution of our environment. Lakhs of trees are planted by people in the month of July every year. The occasion is called

(a) Forest Conservation Day

(b) Van Mahotsav

(c) Plantation month

(d) Wildlife week

► (b) Van Mahotsav

11. Air pollution causes

(a) Global warming

(b) Respiratory diseases

(c) Soil erosion

(d) None of these

► (b) Respiratory diseases

12. The Taj Mahal is being affected due to:

(a) Noise pollution

(b) Air pollution

(c) Water pollution

(d) None of these

► (b) Air pollution

13. Heat is reflected from the earth’s surface and trapped in the atmosphere. Which phenomena is being referred to?

(a) Global warming

(b) Ozone depletion

(c) Greenhouse effect

(d) Thermal pollution

► (c) Greenhouse effect

14. Green house gas is

(a) Nitrogen

(b) Oxygen

(c) Methene

(d) Carbon dioxide

► (d) Carbon dioxide

15. Which of the following does NOT cause air pollution?

(a) Increasing forest reserves

(b) Using pesticides in farms

(c) Developing housing estates

(d) Quarrying for limestone

► (a) Increasing forest reserves

16. The phenomenon of marble cancer is due to

(a) Soot particles

(b) CFCs

(c) Acid rain

(d) Fog

► (c) Acid rain

17. Which one is a common source of drinking water?

(a) Spring water

(b) Ocean water

(c) Sea water

(d) River and lake

► (d) River and lake

18. The water that is purified and fit for drinking is called

(a) Potable water

(b) Pure water

(c) Hard water

(d) Saline water

► (a) Potable water

19. Finer hair inside the nose

(a) Filter the microbes

(b) Prevent the water vapour

(c) Filter the dust particle

(d) Prevent the carbon dioxide gas

► (c) Filter the dust particle

20. The substance that pollute the natural substance is called

(a) Magnifier

(b) Fertilizers

(c) Pollutant

(d) Reactant

► (c) Pollutant

21. How are monuments of marble destroyed?

(a) By sulphur dioxide pollution.

(b) By carbon monoxide pollution.

(c) By pesticide pollution.

(d) By dust particles.

► (a) By sulphur dioxide pollution.

22. Which of these is the major air pollutant in cities like Delhi and Kolkata?

(a) Carbon monoxide

(b) Hydrocarbons

(c) Suspended particulate matter

(d) Oxides of nitrogen

► (c) Suspended particulate matter

23. How are lead particles released into the air?

(a) By burning coal in thermal power stations

(b) By burning petrol in automobiles

(c) By burning biomass in chullahs

(d) By burning LPG for cooking

► (b) By burning petrol in automobiles

24. From which of the following bad effects does the ozone layer in our atmosphere protect us?

(a) Carbon dioxide

(b) CFC’s

(c) The sun’s ultraviolet rays

(d) All of the above

► (c) The sun’s ultraviolet rays

25. Chlorofluorocarbon is used in

(a) Refrigerators

(b) Air conditioners

(c) Aerosol sprays

(d) All

► (d) All

Class 8 Science Chapter 18 Extra Questions and Answers Pollution of Air and Water

Extra Questions for Class 8 Science Chapter 18 Pollution of Air and Water with Answers Solutions

Pollution of Air and Water Class 8 Extra Questions Very Short Answer Type

Question 1.
What is cause for starting of melting of Gangotri glacier?
Answer:
Global warming

Question 2.
Which health problem arises by air pollution?
Answer:
Respiratory problems like asthma, breathlessness, bronchitis, etc.

Question 3.
What is global warming?
Answer:
Increasing temperature in atmosphere.

Question 4.
Which gas is responsible for depletion of ozone layer?
Answer:
Chloroflurocarbons (CFC’s).

Question 5.
What does SPM stand for?
Answer:
Solid particulate matter.

Question 6.
What is the role of activated charcoal in purification of water?
Answer:
It removes finest particles suspended in water.

Question 7.
Name a greenhouse gas.
Answer:
Carbon dioxide, methane, water vapour (any one)

Question 8.
What is the formula of ozone?
Answer:
O₃

Question 9.
Name the agents that pollute air and water.
Answer:
Pollutants

Question 10.
Name the main air polluting gases.
Answer:
Sulphur dioxide, carbon monoxide and nitrogen oxides.

Question 11.
Which radiations are absorbed by CO₂?
Answer:
Infrared radiations

Question 12.
Define eutrophication.
Answer:
Enrichment of water bodies with nutrients like nitrates and phosphates is known as eutrophication.

Question 13.
Name one major source of water pollution.
Answer:
Untreated sewage

Question 14.
What is the function of ozone layer?
Answer:
Ozone layer protects us from ultraviolet rays of the sun.

Question 15.
Name diseases spread through drinking of contaminated water.
Answer:
Diarrhoea, typhoid, etc.

Question 16.
When was the Ganga action plan launched?
Answer:
In 1985

Question 17.
What is smog?
Answer:
The combination of smoke and fog is basically known as smog.

Pollution of Air and Water Class 8 Extra Questions Short Answer Type

Question 1.
What do you mean by water pollution?
Answer:
When water get contaminated by unwanted substances which have a harmful effect on both living and non-living things is referred to as water pollution.

Question 2.
What is the greenhouse effect?
Answer:
The reflected sun rays are trapped by the earth’s atmosphere. The trapped radiation warms the earth.
This process by which the temperature of the earth’s atmosphere rises is called greenhouse effect.

Question 3.
What are the main causes of air pollution?
Answer:
Following are the main causes of air pollution:

• Poisonous gases which are expelled by various industries.
• Gases emitted by vehicles.
• Smoke and dust which are arising day by day due to human activities.
• Smoke emitted by forest fire.

Question 4.
What do you mean by air pollution?
Answer:
When air is contaminated by unwanted substances which have a harmful effect on both living and non¬living things then it is referred as air pollution.

Question 5.
What are the factors that are responsible for water pollution?
Answer:
Water gets polluted when unwanted and harmful substances are added to the water. Discharging of untreated sewage into the river, leaching of chemicals from agricultural practices and industries, oil spills, etc., causes water pollution.

Question 6.
What are the harmful effects of global warming?
Answer:
Following are the harmful effects of global warming:

• It will increase the earth’s temperature.
• Increase in earth’s temperature may lead to rise in sea level due to melting of glaciers.
• Rise in sea level will flood the coastal and low-lying areas.
• Global warming may lead to extreme weather other than cold or heat extremes.
• It may also affect many flora and fauna which are sensitive to temperature and their extinction.

Question 7.
Which factors decides quality of potable water?
Answer:
Potable water is clear, tasteless, odourless, have no contaminants and right pH. It has no harmful minerals or their level is too low to affect human health.

Question 8.
What’is global warming?
Answer:
Carbon dioxide is increasing day by day and it is a warm gas, which increases the temperature of the earth’s atmosphere. It is called global warming.