WBBSE Solutions For Class 10 Physical Science And Environment Chapter 1 Concerns About Our Environment

by

WBBSE Class 10 Physical Science Question Answer In English

Chapter 1 Concerns About Our Environment MCQs

Question 1. The source of heat on the surface of the sun

  1. Nuclear fusion reaction
  2. Nuclear fission reaction
  3. Thermal reaction
  4. Redox reaction

Answer: 1. Nuclear fusion reaction.

Question 2. The fuel used as aviation fuel in jet airplanes is a special grade of :

  1. Petrol
  2. Kerosene
  3. Ethanol
  4. Methanol

Answer: 2. Kerosene.

Read And Learn More: WBBSE Solutions For Class 10 Physical Science And Environment

Question 3. The ozone layer is present in :

  1. Troposphere
  2. Ionosphere
  3. Stratosphere
  4. Mesosphere

Answer: 3. Stratosphere.

Question 4. Sewage water is purified by:

  1. Microorganism
  2. light
  3. Fishes
  4. Aquatic plants

Answer: 1. Microorganisms

 

Question 5. Which of the following is not a constituent of Los Angels smog?

  1. CxHy
  2. 03
  3. NO2
  4. SO2

Answer: 4. SO2

Question 6. Which of the following is a secondary pollutant?

  1. CO2
  2. N2O
  3. PAN
  4. SO2

Answer: 3. PAN.

Question 7. Ozone is stratosphere depleted by :

  1. CF2CL2
  2. C7F6
  3. CF6 CL6
  4. C6F6

Answer: 1. CF2CL2

Class 10 Physical Science Solution WBBSE

Question 8. The smog is essentially caused by the presence of:

  1. O2 and 03
  2. 03 and N2
  3. Oxides of Sulphur and Nitrogen
  4. Oxygen and Nitrogen

Answer: 3. Oxides of sulphur and Nitrogen.

Question 9. The SI unit of calorific value is :

  1. Cal g-1
  2. B Thu g-1
  3. J kg-1
  4. Jg-1

Answer: 3. J kg-1

Question 10. The major source of Co pollution is :

  1. Exhaust from automobiles
  2. Forest fires
  3. Volcanic eruptions
  4. Industrial process

Answer: 1. Exhaust from automobiles.

WBBSE Class 10 Physical Science Question Answer In English

Question 11. Which of the following is not a chemical pollutant?

  1. Solid wastes
  2. Liquid wastes
  3. Pesticides
  4. Noise

Answer: 4. Noise.

Question 12. The minimum wind speed requires for running a wind-mill is :

  1. 50 km/hr.
  2. 15 km/hr.
  3. 25 km/hr.
  4. 10 km/hr.

Answer: 2. 15 km/hr.

Question 13. Which of the following energy sources is not responsible for global warming?

  1. Fossil fuels
  2. Solar energy
  3. Methane hydrate
  4. All

Answer: 2. solar energy.

Class 10 Physical Science Solution WBBSE

Question 14. Among the following fuels whose quality is most bad?

  1. LPG
  2. Methane
  3. Petrol
  4. Coal

Answer: 4. coal.

Question 15. Which of the following gases is responsible for ozone layer depletion?

  1. O2
  2. NO
  3. N2
  4. All of these

Answer:  2. NO

Question 16. The compound present in the maximum amount in acid rain is :

  1. H2CO3
  2. HCI
  3. HNO3
  4. H2SO4

Answer: 4. H2SO4

Question 17. Man-made chemicals responsible for the depletion of the ozone layer is

  1. Ethylene
  2. Acetylene
  3. Teflon
  4. CFC

Answer: 4. CFC.

Question 18. Depletion of the ozone layer causes

  1. Lung cancer
  2. Breast cancer
  3. Blood cancer.
  4. Skin cancer

Answer: 4. Skin cancer.

WBBSE Class 10 Physical Science Question Answer In English

Question 19. The aromatic compounds present as particulates are :

  1. Benzene
  2. Toluene
  3. Poly cyclic hydrocarbons
  4. Nitrobenzene

Answer: 3. Polycyclic hydrocarbons.

Question 20. In any sample of water, it is always found that:

  1. BOD > COD
  2. BOD < COD
  3. BOD = COD
  4. None of these

Answer: 2. BOD < COD

Question 21. The main cause of Minamata disease is

  1. Arsenic pollution
  2. Lead pollution
  3. Cadmium pollution
  4. Mercury pollution

Answer: 4. Mercury Pollution.

Question 22. Excess nitrate in drinking water can cause:

  1. Methenoglo binomial
  2. Kidney damage
  3. Laxative effect
  4. Liver damage

Answer: 1. Methemoglobinemia.

Class 10 Physical Science WBBSE

Question 23. What is the safety limit of arsenic content in drinking water according to WHO?

  1. 0.01mgL-1
  2. 0.1mgL-1
  3. 0.001 mgL-1
  4. 0.05 mgL-1

Answer: 1. 0.01 mgL-1

Question 24. Biosphere is :

  1. The gases enveloping the earth
  2. Earth’s crust
  3. Surface and groundwaters
  4. Region of earth where life exists

Answer: 4. Region of earth where life exists.

Question 25. Energy sources that can be replenished, once they are used up are called:

  1. Renewable sources
  2. Natural sources
  3. Non-renewable sources
  4. Synthetic sources

Answer: 1. Renewable sources.

Question 26. The difference between the output energy and the input energy is termed as :

  1. Net energy output
  2. Maximum output energy
  3. Minimum output energy
  4. Zero output energy

Answer: 4. Zero output energy.

WBBSE Class 10 Physical Science Question Answer In English

Question 27. Which metal is used in connecting wires that connect solar cells in a solar panel?

  1. Copper
  2. Silver
  3. Iron
  4. Gold

Answer: 2. Silver.

Question 28. What is the principle behind a solar power plant?

  1. Light energy changes into electrical energy
  2. Light energy changes into kinetic energy
  3. Heat energy changes into light energy
  4. Light energy changes into heat energy

Answer: 1. Light energy changes into electrical energy.

Question 29. The instrument used for measuring soil salinity is :

  1. Photo meter
  2. Voltameter
  3. Conductivity meter
  4. Calorimeter

Answer: 3. Conductivity meter.

Question 30. The ozone layer of the stratosphere requires protection from the indiscriminate use of:

  1. Pesticides
  2. Atomic explosions
  3. Aerosols and high-flying jets
  4. Balloons

Answer: 3. Aerosols and high-flying jets.

Class 10 Physical Science WBBSE

Chapter 1 Concerns About Our Environment Very Short Answer Type Questions

Question 1. What is COD?
Answer: COD means Chemical Oxygen Demand.

Question 2. Name some methods used in green chemistry.
Answer: The use of sunlight, microwaves, sound waves, and the use of enzymes.

Question 3. What is PCB?
Answer: PCB is polychlorinated biphenyl. It is a highly toxic compound.

Question 4. Name of main compounds causing damage to the ozone layer.
Answer: Nitric oxide (NO) and Freons.

Question 5. In which of the atmospheric layers does the increase in attitude result in an increase in temperature?
Answer: Stratoshere and Thermosphere.

Question 6. Which one is more harmful to the human body-CO or CO2?
Answer: CO is more harmful to the human body.

Question 7. Name two sinks of carbon dioxide.
Answer: Ocean dissolves it and plants which use it for photosynthesis.

Question 8. Which disease is caused due to the formation of holes in the ozone layer and why?
Answer: Ultraviolet rays coming from the sun reach the earth passing through the ozone hole cause skin cancer.

Question 9. What types of aromatic compounds are present as particulates in the air?
Answer: Polycyclic aromatic hydrocarbons (PAH).

WB Class 10 Physical Science Question Answer

Question 10. What is siltation?
Answer: The mixing of soil or rock particles into water is known as siltation.

Question 11. Mention the range of temperature of the atmosphere.
Answer: The range of temperature of the atmosphere is from – 92°C to + 1200°C.

Question 12. What compound is formed when CO gas combines with blood?
Answer: Carboxyhemoglobin.

Question 13. Name some methods of waste management.
Answer: Burning and incineration, recycling process, sewage treatment, and dumping method.

Question 14. What is the main source of carbon monoxide in the atmosphere?
Answer: Coal, petrol, and incomplete combustion of other fossil fuels.

Question 15. Name some gases which are responsible for the greenhouse effect.
Answer: Carbon dioxide (CO2), Methane (CH4), Water vapor (H2O), Cholorofluoro carbon (CFC), Nitrous Oxide (N2O)

WBBSE Class 10 Physical Science Question Answer In English

Chapter 1 Concerns About Our Environment Fill In The Blanks

Question 1. Between NO2 and NO ______ is more harmful.
Answer: NO2

Question 2. The word, ‘PAH’ denotes
Answer: Polyaromatic hydrocarbon.

Question 3. The lung disease caused by silica is _________.
Answer: Silicosis.

Question 4. The total mass of gaseous substances in the atmosphere is nearly
Answer: 5.5×1015 ton.

Question 5. The amount of carbon dioxide in the atmosphere is approximately
Answer: 0.031%

Question 6. CO, When mixed with water, forms_______.
Answer: Carboxyhemoglobin.

Question 7. The methane gas-producing field is ________.
Answer: Paddy field.

Question 8. The full form of TEL is _________.
Answer: Tetra ethyl lead.

Question 9. The smoke of cars pollutes the air as there is __________ gas.
Answer: CO.

Question 10. SO2 and NO2 cause pollution by increasing _________.
Answer: acidity.

Question 11. The word ‘CFC’ means
Answer: Cholorofluoro carbon.

Question 12. London smog is _______ in nature.
Answer: Reducing.

Question 13. The main air pollutants are_____, ______, ______.
Answer: SO2 , SO3 , NO2.

Question 14. The depletion of ozone over Antarctica occurs in _______ season.
Answer: spring.

Question 15. The pH of ordinary rainwater is _______
Answer: 5.6

Question 16. ______ may contain cancer-causing hydrocarbon.
Answer: Sooty smoke.

Question 17. Plants grow ________ in high concentrations of CO2.
Answer: better.

Question 18. The mesosphere and thermosphere are collectively known as ________.
Answer: the ionosphere.

Question 19. Gas released during the Bhopal tragedy was ________.
Answer: methyl iso cyanate (MIC)

Question 20. One remarkable phenomenon that happened in the troposphere is __________.
Answer: Greenhouse.

WB Class 10 Physical Science Question Answer

Question 21. Greenhouse gases can absorb _________ radiation.
Answer: infra-red.

Question 22. The formation of ozone holes increases the tendency of human beings to be attacked by _______.
Answer: Cancer.

Question 23. Depletion of the ozone layer takes place mainly over _________.
Answer: Antarctica.

Question 24. The whirlpool of wind formed in the stratosphere surrounding Antarctica is known as _________.
Answer: Polar vortex.

Question 25. The formation of chlorophyll is retarded in presence of SO. This phenomenon is known as _________.
Answer: Chlorosis.

Question 26. The SI unit of calorific value is ___________.
Answer: Jkg-1

Question 27. Ozone is stratosphere depleted by _________.
Answer: CF2CL2.

Question 28. Sewage water is purified by ________.
Answer: Microorganism.

Question 29. The compound present in the maximum amount in acid rain is _________.
Answer: H2SO4.

Question 30. The biosphere is ________.
Answer: Region of earth where life exists.

WBBSE Class 10 Physical Science Question Answer In English

Chapter 1 Concerns About Our Environment Short Answer Type Questions

Question 1. How does carbon monoxide molecule link to hemoglobin molecule?
Answer:

In the hemoglobin molecule Fe (2) atom is linked to five groups by coordinate bonds and the sixth site remains free. In normal conditions, aerial oxygen O2 links to Fe (2) of this vacant coordination site.

Now carbon monoxide (CO) is a stronger length than oxygen molecule in case of the presence of both CO and O2, CO occupies the vacant coordination site in hemoglobin instead of oxygen.

WBBSE Solutions Guide Class 10

Question 2. What is meant by inversion temperature in different regions of the atmosphere?
Answer:

Inversion temperature: As we proceed from one region of the atmosphere to the next higher region, the trend of temperature changes either from increase to decrease or from decrease to decrease. This trend of either increase or decrease is called inversion temperature.

Question 3. What is siltation?
Answer:

Siltation In this process of mixing soil particles with water. The soil particles present in water procedure turbidity. Due to the turbidity of the water, the free movements of the aquatic organisms in hindered, and as a result their growth and productivity also get reduced.

Question 4. What are combustible and noncombustible materials?
Answer:

Combustible materials: Materials that can be burnt are combustible materials Non-combustible materials: Materials that cannot be burnt are non-combustible materials.

Question 5. What is a solar cell?
Answer:

Solar cell: It is a device that directly converts solar energy into electrical energy.

Question 6. What are the types of sources of energy?
Answer:

Types of sources of energy: There are two types of sources of energy. These are

  1. Renewable sources of energy
  2. Non-renewable sources of energy.

Question 7. What is nuclear fission?
Answer:

Nuclear fission: It is a process in which a heavier nucleus splits into a lighter nucleus with the release of huge amounts of energy.

Question 8. What is destructive distillation?
Answer:

Destructive distillation: It is a process of burning wood in a limited supply of oxygen.

Question 9. What is a windmill?
Answer:

Windmill: It is a device that converts wind energy to mechanical or electrical energy.

Question 10. What is a good source of energy?
Answer:

Good source of energy: A good source of energy should be renewable and environmentally friendly.

Question 11. Define Ocean Thermal Energy (OTE).
Answer:

The energy available due to the difference in the temperature of water at the surface of the ocean and at deeper levels is called ocean Thermal Energy.

Question 12. Define Geothermal energy.
Answer:

Geothermal energy is the heat energy from hot rocks present inside the earth.

Question 13. What is a Biogas plant?
Answer:

A biogas plant consists of locushaped, underground tank, which is made of bricks and has a dome-shaped roof, made of cement and bricks.

Question 14. What is Biogas?
Answer:

Biogas is a mixture of methane, carbon dioxide, hydrogen, and hydrogen sulfide.

Question 15. What is a solar heating device?
Answer:

A device that gets heated by using the sun’s heat energy is called a solar heating device.

WBBSE Class 10 Physical Science Question Answer

Question 16. What is a solar cell?
Answer:

A solar cell is a device that converts solar energy directly into electricity.

Question 17. What do you mean by Biomass?
Answer:

Biomass is the organic matter which is used as fuel to produce energy.

Question 18. What is a solar cooker?
Answer:

The solar cooker is a device that is used to cook food by utilizing the heat energy radiated by the sun.

Question 19. What are Non-renewable sources of energy?
Answer:

Those sources of energy which have accumulated in nature over a very, very long time and cannot be quickly replaced when exhausted are called nonrenewable sources of energy.

Question 20. Write the other name of nonrenewable sources of energy.
Answer:

The name of non-renewable sources of energy is nonconventional sources of energy.

Question 21. What do you mean by renewable sources of energy?
Answer:

These sources of energy which are being produced continuously in nature and are inexhaustible, are called renewable sources of energy.

Question 22. What do you mean by fossil fuel?
Answer:

A natural fuel formed deep under the earth from the pre-historic remains of living organisms (like plants and animals) is caused by fossil fuel.

Question 23. What is the major source of energy for generating electricity in power plants?
Answer:

The major source of energy for generating electricity in power plants is fossil fuels.

Question 24. What is petroleum?
Answer:

The crude oil petroleum is a complex mixture of several solid liquid and gaseous hydrocarbons mixed with water, salt, and earth particles.

Question 25. What do you mean by Hydro-Power plant?
Answer:

A power plant that produces electricity by using flowing water to rotate a turbine is called a hydropower plant.

Class 10 Physical Science WBBSE

Question 26. What is the Green House Effect?
Answer:

Green House Effect is the process of warming a planet’s surface and its Lower atmosphere by the absorption and emission of infrared radiations by atmospheric gases.

Question 27. What do you mean by Global warming?
Answer:

Global warming means the increase in average temperature near the earth’s surface due to an increase in the amount of greenhouse gases in the atmosphere.

Question 28. What is natural gas?
Answer:

Natural gas is a fossil fuel that is found on top of petroleum under the earth.

Question 29. If you could use any source of energy for heating your food, which one would you use and why?
Answer:

We use LPG (Liquefied Petroleum Gas) for heating our food; because it is easily available in our kitchen, gives on smoke on burning, and takes less time to do the job.

Question 30. In which season does the depletion of layar on Antarctica take place and when is it filled up again?
Answer:

During the springtime in Antarctica i.e. in the months of September and October, the depletion of the ozone layer of the stratosphere takes place. But after the spring in the months of November and December, the produced ozone hole is filled up.

Question 31. Give the names of two energy sources that you would consider to be exhaustible. Give reasons, for your choice.
Answer:

Coal and petroleum are exhaustible energy sources because their stock is going to be finished in the near future and it takes millions of years for their formation.

Question 32. Fish do not grow as well in warm water as in cold water-explain why.
Answer:

Explanation: The solubility of gas in water depends on the temperature. Consequently, the amount of soluble oxygen in warm water becomes less than that of cold water. As Oxygen is very essential for the respiration and growth of fish in water, the growth of fish becomes less in warm water.

Question 33. What is chlorosis?
Answer:

Chlorosis: The process of sulfur dioxide gas in the atmosphere retards the production of chlorophyll in the leaves of plants. In consequence of which the green colour of leaves is lost this phenomenon of the disappearance of the green color of leaves is known as chlorosis.

Question 34. Name two energy sources that you would consider to be renewable. Give reasons for your choice.
Answer:

Solar energy and wind energy are examples of renewable energy sources because they get quickly replenished.

Class 10 Physical Science WBBSE

Question 35. What are the disadvantages of fossil fuels?
Answer:

Disadvantages of fossil fuels :

The following are the dis advantage of fossil fuels:

  1. These are non-renewable.
  2. They produce air pollutants on burning.

Question 36. What is a hydroelectric power plant?
Answer:

Hydroelectric power plant: In this power plant energy from flowing water is utilized to produce electricity on a large scale.

Question 37. What are the disadvantages of a solar cooker?
Answer:

The disadvantages of a solar cooker are:

  1. The direction of the reflector of a solar cooker has to be changed from time to time to keep it facing the seen.
  2. The box-type solar cooker cannot be used for baking or for frying.
  3. If the day sky is covered with clouds, even then solar cookers cannot be used to work food.
  4. The solar cooker cannot be used to cook food during nighttime.

Question 38. What do you mean by a solar constant?
Answer:

Solar constant: The amount of solar energy received per second by one square meter area of the near-earth space (exposed perpendicularly to the rays of the sun at an average distance between the sun and the earth, is called the solar constant.

Question 39. What is a solar heating device?
Answer:

Solar heating device: A device that gets heated by using Sun’s heat energy is called a solar heating device.

Question 40. Write a short note on the advantages of LPG.
Answer:

The advantages of LPG :

  1. LPG burns with a smokeless flame and so does not cause air pollution.
  2. LPG does not produce any poisonous gases on burning.
  3. LPG is easy to handle and convenient to store.
  4. LPG is a very neat and clean domestic fuel.

Question 41. ‘Natural gas is used as a fuel for a number of purposes’- Explain it.
Answer:

  1. Natural gas is used as a domestic and industrial fuel.
  2. Natural gas is used as a fuel in thermal power plants for generating electricity.
  3. Compressed Natural gas is being used increasingly as a fuel in transport vehicles.

Class 10 Physical Science WBBSE

Chapter 1 Concerns About Our Environment Broad Answer Type Questions

Question 1. What is good fuel?
Answer:

Good fuel: Good fuel should have many desirable characteristics. Some of these are as follows:

  1. It should produce a high amount of energy for each limit of mass or volume.
  2. It should be easily available and should be easy to transport.
  3. It should be economical.

Question 2. What are the advantages of nuclear energy?
Answer:

The advantages of nuclear energy are as follows: A small amount of radioactive material can generate a huge amount of energy. It does not produce air pollution. A nuclear power plant is more efficient than other power plants.

Question 3. Hydrogen has been used as a rocket fuel would you consider it a cleaner fuel than LPG? Why and why not?
Answer:

Hydrogen is a much cleaner energy source than CNG. CNG is derived from biomass and hence burning the CNG causes air pollution, although on a much smaller scale than coal and petroleum. The use of hydrogen as an energy source does not pollute gases.

Question 4. Can any source of energy be pollution free? Why and why not?
Answer:

Many sources of energy can be pollution free when the burning of biomass is not involved in the production of energy, then there is no chance of pollution. For example, wind energy, solar energy, hydel energy, etc are pollution free.

Class 10 Physical Science WBBSE

Question 5. What are the limitations of the energy that can be obtained from the oceans?
Answer:

Limitations of energy that can be obtained from the oceans:

These forms of energy can be used only in coastal areas, which would leave a vast portion of human habitation. The technologies for using these energies are still at the experimental stage and hence are very costly and less efficient.

Question 6. Why are looking for an alternate source of energy?
Answer:

Because of the growing population, the energy demand is rising. Fossil fuels are going to be exhausted in the near future and burning them is causing air pollution. Hence, we need to find an alternate source of energy which renewable and environmentally friendly.

Question 7. How has the traditional use of wind and water energy been modified for our convenience?
Answer:

  • Before the beginning of the Industrial Revolution, wind and water energy were used for serving many purposes but the ways of their use were not efficient. For example, windmills were used to power smaller mills like flour mills or sawmills.
  • The flow of water was used for transporting wooden logs. Now a day, both wind energy and water energy are being widely used to produce electricity, which means better and more efficient use of these forms of energy.

Question 8. What kind of mirror, concave or convex, or plain would be best suited for use in a solar cooker? Why?
Answer:

Explanation: A concave mirror is best suited for use in a solar cooker. The reason for this is the ability of a concave mirror to converge the solar energy at a point. This enables the concave mirror to produce a larger amount of heat compared to other types of mirrors.

Question 9. Short Note-Ozone Layer.
Answer:

  • The ozone layer is contained within the stratosphere. In this layer, ozone concentrations are about 2 to 8 parts per million which is much higher than in the lower atmosphere but very small compared to the main components of the atmosphere.
  • It is mainly located in the lower portion of the stratosphere from about 15:35 km though the thickness varies seasonally and geographically. About 90% of the ozone in the Earth’s atmosphere is contained in the atmosphere.

Question 10. What is ultraviolet light? How can the ozone Layer deplete?
Answer:

Although the concentration of ozone in the ozone layer is very small. It absorbs biologically harmful ultraviolet radiation coming from the sun: Extremely short or vacuum UV is screened out by nitrogen. UV radiation is capable of penetrating nitrogen.

  • The Ozone layer can be depleted by free radical catalysts including nitric oxide, hydroxyl, atomic chlorine, and atomic bromine. While there are natural sources for all of these species.
  • The concentrations of chlorine and bromine increased markedly in recent decades due to the release of large quantities of man-made organohalogen compounds, especially chloroform carbons, and bromoform carbons.

Question 11. Short Note-Exosphere.
Answer:

Exosphere: The exosphere is the outermost layer of Earth’s atmosphere. It extends from the exobase, Which is Located at the top of the Thermosphere at an altitude of about 700 km. above sea level, to about 10,000 km.

The exosphere merges with the emptiness of outer space, where there is no atmosphere. This layer is mainly composed of extreme hydrogen, helium, and several heavier molecules including nitrogen, oxygen, and carbon dioxide closer to the exobase.

Question 12. Draw a diagram of a solar cell.
Answer:

WBBSE Solutions For Class 10 Physical Science And Environment Chapter 1 Concerns About Our Environment Solar Cell

WB Class 10 Physical Science Question Answer

Question 13. Short Note. Thermosphere.
Answer:

Thermosphere: The thermosphere is the second highest layer of Earth’s atmosphere. It extends from the Mesopause at an altitude of about 80 km. upto the thermopause at an altitude range of 500-1000km.

  • The height of the thermopause varies considerably due to changes, in solar activity. This layer is completely cloudless and free of water vapor.
  • However non-hydrometeorological phenomena such as aurora Borealis and aurora australis are occasionally seen in the thermosphere. The Internation Space Station orbits in this layer, between 320 and 380 km.

Question 14. Short Note-Mesosphere.
Answer:

Mesosphere: The mesosphere is the third highest layer of Earth’s atmosphere, occupying the region above the stratosphere and below the thermosphere. It extends from the stratopause at an altitude of about 50 km. to the mesopause at 80-85 km above Sea level.

  • Temperatures drop with increasing altitude to the mesopause that marks the top of this middle layer of the atmosphere. It is the coldest place on earth and has an average temperature around-85°C.
  • The mesosphere is the layer where most meteors burn up upon the atmospheric entrance. It is too high above Earth to be accessible to aircraft and balloons and too low to permit orbital spacecraft. The mesosphere is mainly accessed by sounding rocks.

Question 15. Short Note-Stratosphere.
Answer:

Stratosphere The Stratosphere is the second lowest layer of Earth’s atmosphere. It lies above the troposphere and is separated from it by the tropopause. This layer extends from the top of the troposphere at 12km about the earth’s surface to the stratopause at an altitude of about 50 to 55 km.

  • The atmospheric pressure at the top of the stratopause is 1/1000 the pressure at sea level. It contains the ozone layer, which is the part of Earth’s atmosphere that contains relatively high concentrations of gas.
  • The stratospheric temperature profile creates very stable atmospheric conditions, So The layer lacks the weather-producing air turbulence that is prevalent in the troposphere.

Question 16. Short Note-Green House Effect.
Answer:

Green House Effect: The earth’s atmosphere is transparent to the visible light and infrared radiations of short wavelengths coming from the sun.

  • The high-energy radiations (gamma rays. X-rays, Ultraviolet rays) are absorbed by the ozone layer while the low-energy radiations (infrared radiation) of long wavelengths and radiowaves are reflected back into space by the ionosphere.
  • The solar radiations which pass through the atmosphere of the earth are absorbed by the clouds, earth, surface, and seawater due to which the earth’s surface gets heated up.
  • Now earth’s surface radiates infrared radiations of long wavelengths, but these radiations are reflected back by the clouds and absorbed by the gases present in the atmosphere of the earth and thus the clouds and gases prevent them from escaping into space. Thus keeping the earth’s atmosphere warm.

WB Class 10 Physical Science Question Answer

Question 17. Briefly describe the thermal power plant.
Answer:

Thermal power plant :

A power plant in which the heat required to make steam to drive turbines is obtained by burning fuels is called a thermal power plant.

  • Coal is burned in a furnace F to produce heat. This heat boils the water in a boiler B to form steam.
  • The steam formed from the boiling water builds up. a pressure. The hot steam at high pressure is introduced into turbine chamber C having a steam (Picture) turbine T, The steam passes over the blades of the turbine as a high-pressure jet making the turbine rotate.
  • The shaft S on cooling, stem condenses to form water. This water is again sent to the boiler to form fresh steam. The process is repeated again and again.
  • Since it is easier to transmit electricity over long distances than to carry coal over the same distance, therefore, many thermal power plants are established near coal fields.
  • We produce a major part of our electricity by burning fossil fuels. Due to this, large amounts of fossil fuels are being burnt every day at thermal power plants to generate electricity.
  • Because our supplies of coal, oil, and gas are running out at a rapid rate and because of the pollution caused by burning fossil fuels, other ways of generating electricity must be found.
  • Please note that electricity is not fuel. It is a form of energy. At thermal power plants. It is the chemical energy of fossil fuels that is transformed into electrical energy.

Question 18. What is the cause of global warming? What are the effects of global warming? Write the advantages of generating hydroelectricity.
Answer:

The cause of global warming :

  • The concentration of chlorofluorocarbons has increased by 5% per year.
  • The concentration of methane has doubled due to agricultural sources (vice cultivation, animal husbandry, natural gas exploration, burning of biogas)
  • The concentration of carbon dioxide has increased up to 25% due to industrial growth, combustion of fossil fuel, and clearing of forests.

The effect of global warming :

  • It will increase the frequency and intensity of extreme weather events (floods, droughts, heat waves, hurricanes) because of changes in the pattern of winds and ocean currents.
  • It will result in low agricultural yield.

The advantages of Generating Hydroelectricity?

  • The generation of electricity from flowing water does not produce any environmental pollution.
  • The construction of dams on rivers helps in controlling floods, and in irrigation.
  • Flowing water is a renewable source of electric energy that will never get exhausted.

Leave a Comment