DAV Class 8 Science Solution Chapter 19 Pollution of Air
DAV School Books Class 8 Science Solution Chapter 19 Pollution of Air all Question Answer. DAV Class 8 19th Chapter Pollution of Air full Chapter explanation by expert teacher.
DAV School Books Class 8 Science Solution Chapter 19 Pollution of Air
A.) Fill in the blanks.
1.) ___________ and ___________ gases dissolve in water to form acid rain.
2.) The phenomena of corrosion of marbles of the monument, by acid rain, is called ___________.
3.) ___________ and ___________ are two of the main greenhouse gases.
4.) The phenomenon, of likely increase in earth’s average temperature (due to increase in the amount of greenhouse gases), is known as ___________.
Answer: (1) Nitrogen dioxide, sulphur dioxide (2) marble cancer (3) carbon dioxide, methane (4) global warming.
B.) State True or False for the following statements.
1.) Burning of fossil fuels is one of the many causes of air pollution.
2.) High concentration of nitrogen dioxide, in the atmosphere, can result in respiratory problems.
3.) The ultraviolet rays of the sun get absorbed mainly by the oxygen present in the atmosphere.
4.) Acid rain does not corrode metals.
5.) Sulphur dioxide is one of the ‘greenhouse gases’.
Answer: (1) True (2) True (3) False, It gets absorbed by the ozone in the ozone layer (4) False, It corrodes metals as well as limestone and marble (5) False, Carbon dioxide is a greenhouse gas.
C.) Tick the correct option.
1.) Which of the following is responsible for depletion of ozone layer?
Answer: chlorofluorocarbon.
2.) An increase, in the amount of carbon dioxide and methane in the atmosphere, is likely to lead to-
Answer: global warming.
3.) The main gases, that trap the solar heat radiations after their reflection from the earth, are-
Answer: carbon dioxide, methane, water vapours.
4.) Taj Mahal, at Agra, may get damaged if its surrounding atmosphere contains more of-
Answer: sulphur dioxide.
5.) Smoke combines with water vapours and dust particles, in the presence of sunlight, to form-
Answer: smog
D.) Answer the following questions in brief.
1.) Define the term ‘pollutant’.
Any item or substance that is released into the atmosphere and damages the natural environment or causes harm to living things is considered a pollution. Pollutants can arise from a range of sources, including industrial processes, vehicular movement, and agricultural operations. They can also take the form of gasses, liquids, or solids.
Answer: a substance that can harm when it is present in greater quantities than its natural abundance in the environment.
2.) State two causes of air pollution.
Answer: The two causes of air pollution are as follows:
- Emissions from vehicles including cars, buses, lorries, and motorcyclists are one of the main contributors of air pollution.
- Industrial processes like mining, manufacturing, and power generating are major contributors to air pollution. Pollutants such sulphur dioxide, nitrogen oxides, including fine particles are released into the atmosphere as a result of these operations..
3.) How is carboxy haemoglobin formed?
Answer: When carbon monoxide attaches to the haemoglobin in red blood cells, carboxyhemoglobin is created. Red blood cells include a protein called haemoglobin, which binds to oxygen and aids in carrying it throughout the body.
4.) State the harmful effects of chlorofluorocarbons.
Answer: The ozone layer is where CFCs can ascend into the atmosphere and break down due to ultraviolet light, releasing toxins and chloride atoms. After then, these atoms function as catalysts, disintegrating ozone molecules and thinning the ozone layer. This causes the ozone layer to get damaged, especially over Antarctica.
5.) Suggest any three measures that can help to check global warming.
Answer: The three methods are as follows:
- Reducing the quantity of greenhouse emissions into the atmosphere is among the best strategies to slow global warming down.
- Reforestation and tree planting can help remove the carbon dioxide in the atmosphere.
- Investments in renewable energy sources like hydroelectric, solar, and wind can aid in lowering greenhouse gas emissions.
E.) Answer the following questions.
1.) Give the meaning of the term ‘smog’. List its harmful effects.
Answer: Smoke and fog combine to form smog, a form of air pollution. Pollutants including nitrogen oxides, sulphur dioxide, as well as gases that are released into the air combine with sunlight to create a thick, hazy mixture, which is the main source of smog.
Its effects are as follows:
- Breathing Problems:
- Creates a Sunlight barrier:
2.) Write a short note on ‘acid rain’.
Answer: A form of rainfall known as “acid rain” has an acidity balance that is lower than average. It is brought on by the atmospheric release of sulphur dioxide (SO2) plus nitrogen oxides (NOx), which react with water vapour to produce sulfuric acid and nitric acid, respectively. These acids are transported by the winds and may disperse as acid rain, snowfall, hail, or fog before reaching the land. Acid particles that land on surfaces without precipitating can potentially cause acid rain in the form of dry deposition.
3.) List the main causes of increase in concentration of greenhouse gases in the atmosphere.
Answer: The main causes are:
- Fossil Fuels: The main cause of emissions of greenhouse gases is the use of coal, petroleum, and oil and gas for energy production. When these fossil fuels are burned, carbon dioxide (CO2) as well as other gases are released into the atmosphere.
- Deforestation: In addition to other land use changes, deforestation can increase greenhouse gas emissions. The carbon that trees collect and store is emitted into the atmosphere when they are chopped down or burned.
- Energy Production: Large volumes of greenhouse gases are also released during the production of electricity using non-renewable resources like coal and natural gas.
4.) State the likely consequences of an increase in the ‘greenhouse effect’.
Answer: Global warming, or an increase in the average surface temperature of the Earth, is the most well-known result of the greenhouse effect. Numerous effects, including more frequent and intense heat waves, floods, as well as cyclones, may result from this.
5.) Write any five methods that can help to control air pollution.
Answer: The five methods are:
- Planting Trees
- Utilisation of unleaded petrol in vehicles.
- Utilisation of CNG in vehicles.
- Afforestation.
- Utilisation of smokeless chulhas.