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CBSE Sample Paper Class 8 Science Pollution of Air and Water
1.) Answer the short questions (11×1)
a.) What is air pollution?
b.) What are air pollutants?
c.) What is smog?
d.) What is the full form of CFC.
e.) Mention one harmful effect caused by air pollution to our body.
f.) What is global warming?
g.) What are greenhouse gases?
h.) What are water pollutants?
i.) What is ganga action plan?
j.) What is potable water?
k.) Which substance is used to purify water?
2.) Briefly answer the following questions (8×3)
a.) Describe how air gets polluted.
b.) Name some poisonous gas which cause air pollution.
c.) How air pollution is effecting Taj Mahal?
d.) What is greenhouse effect?
e.) Briefly describe global warming.
f.) Mention the steps to reduce air pollution.
g.) Mention the causes of water pollution.
h.) How to reduce water pollution?
3.) Fill in the blanks (5×1)
a.) _________ found in refrigerators causes air pollution.
b.) _________ and ________ mixes with rain and causes acid rain.
c.) Carbon dioxide is a _______ gas.
d.) Ganga river cleaning mission ___________ was launched in 2016.
e.) While using water our mantra should be recycle, ______ and _____ .
4.) Write true or false (5×1)
a.) We can live without air.
b.) Global warming is harmful for our environment.
c.) Sewage water is safe to drink.
d.) Cholera is caused by air pollution.
e.) Smog causes asthma.
5.) Fill the table (5×1)
Pollutants | Source | Effects |
Carbon monoxide | ||
Chlorofluorocarbons | ||
Smog | ||
Pesticides and weedicides | ||
Arsenic and lead |
Answers
1.) Answer the short questions (11×1)
a.) What is air pollution?
Answer –Air pollution is the condition in which air is filled with harmful substances which causes harm to both living and non-living.
b.) What are air pollutants?
Answer –The substances which contaminate the air and causes air pollution are called air pollutants.
c.) What is smog?
Answer –Smog is the mixture of smoke which contains harmful air pollutants and fog.
d.) What is the full form of CFC.
Answer –The full form of CFC is chlorofluorocarbon.
e.) Mention one harmful effect caused by air pollution to our body.
Answer –Air pollution can decrease the oxygen carrying capacity of blood.
f.) What is global warming?
Answer –Excessive amount of CO2 or Carbon dioxide in our atmosphere traps the heat and doesn’t allow it to escape to the space. This causes increase in temperature. This is called global warming.
g.) What are greenhouse gases?
Answer – The gases such as methane, nitrous oxide which causes global warming are called greenhouse gases.
h.) What are water pollutants?
Answer –When harmful substances gets mixed with water, it pollutes water. This harmful substances are called water pollutants.
i.) What is ganga action plan?
Answer –Ganga action plan was launched in 1985 to save the Ganga river by reducing the pollution level of the river.
j.) What is potable water?
Answer –Safe and suitable water to drink is called potable water.
k.) Which substance is used to purify water?
Answer –Chlorine is used to purify water.
2.) Briefly answer the following questions (8×3)
a.) Describe how air gets polluted.
Answer – Air gets polluted by the following ways,
- Smoke from different types of vehicles.
- Volcanic eruption, forest fires.
- Smoke from power plants, factories, burning of different materials.
- Chlorofluorocarbon released by refrigerators and air conditioners.
b.) Name some poisonous gas which causes air pollution.
Answer – Some poisonous gas which causes air pollution are carbon dioxide, carbon monoxide, nitrogen oxide, methane etc.
c.) How air pollution is effecting Taj Mahal?
Answer –Lots of industrial factories are located at the nearby areas of Taj Mahal. These factories release harmful pollutants such as sulphur dioxide and nitrogen dioxide. These gases mix with water vapour and form sulphuric acid. This sulphuric acid mixes with rain and causes acid rain. This acid rain when falls on Taj Mahal causes discoloration of the white marble of Taj Mahal.
d.) What is greenhouse effect?
Answer –In a greenhouse, the heat of the Sun is allowed to get in but can’t go outside. This traps the heat and warms the greenhouse chamber.
Similar things happens with Earth. When there is an increase of greenhouse gases, the radiation of Sun traps inside our atmosphere and warms the environment. This is known as greenhouse effect.
e.) Briefly describe global warming.
Answer –Increasing amount of Carbon dioxide in environment causes greenhouse effect or it traps the heat in our atmosphere and warms the environment. This causes worldwide increase in temperature. This is called global warming.
f.) Mention the steps to reduce air pollution.
Answer – The steps to reduce air pollution includes,
- We should use CNG and unleaded petrol which reduces the air pollutants.
- We need to switchover to cleaner alternative energy such as solar energy, hydropower, wind energy etc.
- We should plant more trees.
- Spread general awareness among people about harmful effects of air pollution.
g.) Mention the causes of water pollution.
Answer – The causes of water pollution includes,
- Sewage water mixing with drinking water.
- Toxic chemicals released by industrial plants.
- Bathing, washing, throwing garbage in water bodies.
- Using chemical fertilizers, weedicides and pesticides in field.
h.) How to reduce water pollution?
Answer – Water pollution can be reduced by following steps
- We should not waste water.
- We should always follow reduce, reuse and recycle rule while using water.
- Industries should properly treat water before draining them.
- We shouldn’t throw garbage in water.
3.) Fill in the blanks (5×1)
a.) Chlorofluorocarbons found in refrigerators causes air pollution.
b.) Sulphur dioxide and nitrogen dioxide mixes with rain and causes acid rain.
c.) Carbon dioxide is a greenhouse
d.) Ganga river cleaning mission National mission for clean Ganga was launched in 2016.
e.) While using water our mantra should be reduce, reuse and recycle .
4.) Write true or false (5×1)
a.) We can live without air.
Answer –False
b.) Global warming is harmful for our environment.
Answer – True
c.) Sewage water is safe to drink.
Answer – False
d.) Cholera is caused by air pollution.
Answer – False
e.) Smog causes asthma.
Answer – True
5.) Fill the table (5×1)
Pollutants | Source | Effects |
Carbon monoxide | Vehicles | Reduce oxygen carrying capacity of blood |
Chlorofluorocarbons | Refrigerators, air conditioners | Damage the ozone layer of the atmosphere |
Smog | Smoke from vehicles and factories | Asthma, cough |
Pesticides and weedicides | Crop field | Pollute ground water |
Arsenic and lead | Factories | Toxicity |