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

Detailed explanations in West Bengal Board Class 10 Physical Science Book Solutions Chapter 1 Concerns About Our Environment offer valuable context and analysis.

WBBSE Class 10 Physical Science Chapter 1 Question Answer – Concerns About Our Environment

Very Short Answer Type Questions :

Question 1.
In which of the atmospheric layers does the increase in altitude result in increase in temperature?
Answer:
Stratosphere and Thermosphere.

Question 2.
Which one is more harmful to the human body – CO or CO₂ ?
Answer:
CO is more harmful to the human body.

Question 3.
In which of the layers of atmosphere does temperature decrease with increase in altitude?
Answer:
Troposphere and Mesosphere.

Question 4.
Mention the range of temperature of the atmosphere ?
Answer:
The range of temperature of the atmosphere is from -92° C to + 1200° C.

Question 5.
What is the main source of carbon monoxide in the atmosphere ?
Answer:
Coal, Petrol and incomplete combustion of other fossil fuels.

Question 6.
Which of the atmospheric layers contains maximum ozone gas?
Answer:
Stratosphere.

Question 7.
Name some gases which are responsible for green house effect.
Answer:
Carbon dioxide (CO₂), Methane (CH₄), Water vapour (H₂O), Chlorofluoro carbon (CFC), Nitrous Oxide (N₂O).

Question 8.
Name the sources of dissolved oxygen in water ?
Answer:
The sources of Oxygen in water are the atmospheric oxygen or the photosynthesis carried out by the plants in water during daylight.

Question 9.
Name of the main compounds causing damage to the ozone layer?
Answer:
Nitric oxide (NO) and Freons.

Question 10.
What compound is formed when CO gas combines with blood ?
Answer:
Carboxy haemoglobin.

Question 11.
Which disease is caused due to the formation of hole 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 12.
Name some methods of waste managment ?
Answer:
B urning and incineration, recycling process, sewage treatment and dumping method.

Question 13.
Name some methods used in green chemistry ?
Answer:
The use of sunlight, micro-waves, sound waves and the use of enzymes.

Question 14.
What is COD?
Answer:
COD means chemical Oxygen Demand.

Question 15.
Name some methods used in green chemistry.
Answer:
The use of sunlight, microwaves, sound waves and the use of enzymes.

Question 16.
Name two sinks of carbondioxide.
Answer:
Ocean which dissolves it and plants which use it for photosynthesis.

Question 17.
What type of pollution effects the sea birds ?
Answer:
Oil pollution.

Question 18.
What are the main sources of thermal pollution ?
Answer:
Nuclear plants and Thermal power plants.

Question 19.
What is siltation ?
Answer:
The mixing of soil or rock particles into water is known as siltation.

Question 20.
Which gas was responsible for so many deaths in Bhupal tragedy?
Answer:
The gas methyl isocyanate (MIC) was responcihle to many deaths in Bhupal.

Question 21.
What type of aromatic compounds are present as particulates in the air?
Answer:
Polycyclic aromatic hydrocarbons (PAH).

Question 22.
What are silicosis and asbestosis ?
Answer:
Lung disease caused by the particulates of silica is called silicosis and that caused by particulates as asbestos is called asbestosis.

Question 23.
What class of people are generally susceptible to attack of black lung and white lung diseases.
Answer:
Generally workers of coal mines and those of cotton mills become victims of black lung and white lung diseases respectively.

Question 24.
What is PCB ?
Answer:
PCB is polychlorinated biphenyl. It is a highly toxic compound.

Question 25.
Why does the population of fish get hindered in thermally polluted water ?
Answer:
Thermal pollution increases the temperature which in turn decreases the DO level of the water. Thus it affects the fishes badly and their growth gets retarded.

Question 26.
What is chlorosis ?
Answer:
The presence of SO_x in the atmosphere as pollutant slows down the production of chlorophyll in the leaves of the plants and the green colour disappears. The phenomenon is called chlorosis.

Question 27.
Why high and low tides occur in sea ?
Answer:
Due to the gravitational pull of sun and moon on the spinning earth, the level of water in the sea rises and falls, these are referred to as the “high tide’ and ‘low tide’.

Question 28.
Thal energy is converted to what form of energy for use ?
Answer:
Electrical energy.

Question 29.
Where in the world geothermal energy is used to generate electricity ?
Answer:
Due to geological changes, some molten hot rocks are formed in the deeper region’s of the earth’s crust and are pushed upward and traped in some regions. In some places heat comes from the fission of radioactive material naturally present in the rocks.

Question 30.
Name a petro-crops.
Answer:
At present Euphorbias plants contain latex of high carbon content, thermal cracking of this latex produce bio-petrol or diesel. These plants are called petro-crops.

Question 31.
What is the name of anaerobic bacteria used for the fermentation of blomass ?
Answer:
Methanogenic bacteria.

Short Answer Type Questions :

Question 1.
What are combustible and non-combustible materials ?
Answer:
Combustible materials : Materials that can be burnt are combustible materials. Non-combustible materials : Materials that cannot be burnt are noncombustible materials.

Question 2.
What are the types of sources of energy?
Answer:
Types of sources of energy: There are two types of sources of energy. These are : (i) Renewable sources of energy. (ii) Non-renewable sources of energy.

Question 3.
What is nuclear fission?
Answer:
Nuclear fission : It is a process in which a heavier nucleus splits into lighter nuclei with release of huge amounts of energy.

Question 4.
What is a petroleum? What is natural gas?
Answer:
(i) Petroleum: An oil derived from rocks. A complex mixture of hydrocarbons. (ii) Natural gas : Natural gas is a fossil fuel that is found on the top of petroleum under the earth.

Question 5.
What is destructive distillation.
Answer:
Destructive distillation : It is a process of burning wood in limited supply of oxygen.

Question 6.
What is hydroelectric power plant ?
Answer:
Hydroelectric power plant : In this power plant energy of flowing water is utilized to produce electricity on a large scale.

Question 7.
What is wind mill?
Answer:
Wind mill : It is a device that converts wind energy to mechanical or electrical energy.

Question 8.
What is a solar cell?
Answer:
Solar Cell : It is a device that directly converts solar energy into electrical energy.

Question 9.
What is good source of energy ?
Answer:
Good source of energy : A good source of energy should be renewable and environment friendly.

Question 10.
What are the disadvantages of fossil fuels ?
Answer:
Disadvantages of fossil fuels: Following are the disadvantages of fossil fuels: (i) These are non-renewable (ii) The produce air pollutants on burning.

Question 11.
What is geothermal energy?
Answer:
Geothermal energy : The energy which can be hamessed from the heat of inside of the earth is called geothermal energy.

Question 12.
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 13.
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.

Question 14.
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 15.
Fish do not grow as well in warm water as in cold water-explain why.
Answer:
Explanation: The solubility 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, so the growth of fish becomes less in warm water.

Question 16.
What is chlorosis ?
Answer:
Chlorosis: The process of sulpherdioxide gas in the atmosphere retards the production of chlorophyll in the leaves of the plants. In consequence of which the green colour of leaves is lost. This phenomenon of disappearance of green colour of leaves is known as chlorosis.

Question 17.
What is siltation ?
Answer:
Siltation: In this process of mixing of soil particles with water. The soil particles present in water procedure turbidity. Due to the turbidity of water, the free movements of the equatic organisms is hindered and as a result their growth and productivity also get reduced.

Question 18.
In which season the depletion of ozone layer on Antarctica take place and when is it filled up again ?
Answer:
During the spring time in Antarctica i.e. in the months of September and October, the depletion of 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 19.
What is meant by inversion temperature in different regions of atmosphere?
Answer:
Inversion temperature: As we proceed from one region of atmosphere to the next higher region, the trend of temperature changes either from increase to decrease or from decreaseto increese. This trend of either increase or decrease is called inversion temperature.

Question 20.
How does carbon monoxide molecule link to haemoglobin molecule?
Answer:
Explanation: In haemoglobin molecule Fe(II) atom is linked to five groups by coordinate bonds and the sixth site remains free. In normal condition aerial oxygen O₂ links to Fe (II) of this vacant coordination site. Now carbon monoxide (CO) being a stronger legand than oxygen molecule in case of the presence of both CO and O₂, CO occupies the vacant coordiriction site in haemoglobin instead of oxygen.

Broad Answer Type Questions

Question 1.
What is a good fuel ?
Answer:
Good fuel: A good fuel should have many desirable characteristics. Some of these are as follows:

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

Question 2.
Why are we looking for alternate source of energy ?
Answer:
Because of 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 environment-friendly.

Question 3.
How has 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 saw mills. The flow of water was used for transporting wooden logs. Now-adays, both wind energy and water energy are being widely used to produce electricity, which means a better and more efficient use of these forms of energy.

Question 4.
What kind of mirror, concave or convex or plain would be best suited for use in a solar cooker? Why ?
Answer:
Explantation : 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 mirror.

Question 5.
What are the limitations of the energy that can be obtained from the oceans?
Answer:
Limitations of energy which can be obtained from the oceans :
These forms of energy can be used only in coastal areas, which would leave a vast portion of the human habitation. The technologies for using these energies are still at experimental stage and hence are very costly and less efficient.

Question 6.
What are the advantages of nuclear energy ?
Answer:
Advantages of nuclear energy are as follows: A small amount of radioactive material can generate a huge amount energy. It does not produce air pollution. A nuclear power plant is more efficient than other power plants.

Question 7.
Can any source of energy be pollution-free? Why and why not ?
Answer:
Many sources of energy can be pollution-free when burning of biomass is not involved in production of energy, then there is no chance of pollution. For example, wind energy, hydel energy, solar energy etc. are pollution-free.

Question 8.
Hydrogen has been used as a rocket fuel would you consider it a cleaner fuel than CNG ? 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. Use of hydrogen as energy source does not polluting gases.

Brain Storming Questions :
Very Short Answer Type Questions :

Question 1.
In which layer of atmosphere least temperature is found?
Answer:
Mesopause, the upper part of mesosphere, is the coldest region having an average temperature around -85° C.

Question 2.
Why ionosphere is so called ?
Answer:
Ionosphere has ions and electrons produced due to different types of ionization reactions occuring there in presence of high energy solar uv radiation. For this reason it is called so.

Question 3.
What is a ‘moisture trap’ and why is it called so ?
Answer:
Tropopause is called ‘moisture trap’. Most of water vapour of stratosphere enters through the tropopause by virtue of its low temperature leaving stratosphere dry. For this reason tropopause is called so.

Question 4.
What is an ozone hole?
Answer:
Ozone hole is a region of expectionally depleted ozone in the stratosphere of the ozone layer in high altitudes i.e., the Antartic, chiefly in winter, attributed to chemical action of CFCs and other atmospheric pollutants resulting in an increase in ultraviolet rays at ground level which gives rise to an increased rink of skin cancer.

Question 5.
What do you mean by ODS ?
Answer:
The chemical substances which catalyse and accelerate the depletion of ozone are called ozone-depleting substances (ODS).
Example :
Chlorofluorocarbons (CFCs), Halons etc.

Question 6.
What is Dobson unit (DU) ?
Answer:
The Dobson unit (DU) is a unit of measurement of the columner density of a trace gas in the earth’s atmosphere.

Question 7.
Global warming is a consequence of which phenomenon ?
Answer:
Global warming is a direct consequence of greenhouse effect.

Question 8.
Name one compound which has approximately 20 times more green house effect than carbondloxide.
Answer:
Methane (CH₄) has approximately 20 times more green house effect than CO₂.

Question 9.
What is a greenhouse ?
Answer:
Greenhouse is a glass house used for raising plants, vegetables, fruits and flowers within it in cold temperature regions where growing of crops in the open field is not possible due to low temperature or cold.

Question 10.
Is the greenhouse effect applicable for earth only ?
Answer:
No, in the solar system, the atmospheres of Venus, Mars and Titan also contain gases that cause a greenhouse effect.

Question 11.
Name any two radiations emitted by the sun that are not visible to the human eye.
Answer:
Infrared radiation and ultraviolet radiation are not visible to the human eye.

Question 12.
Which one is the principle greenhouse gas ?
Answer:
When ranked by their direct contribution to the greenhouse effect, apart from water vapour, Carbon dioxide stands as the principal greenhouse gas.

Question 13.
Name a non-renewable source of energy other than fossil fuels.
Answer:
Nuclear energy is another category of non-renewable source of energy other than fossil fuels.

Question 14.
What is the empirical formula of methane hydrate?
Answer:
The empirical formula of methane hydrate is (CH₄)₄ .(H₂ O)₂₃.

Question 15.
Which process is the basis for the formation of biomass ?
Answer:
Photosynthesis is the basic process for the formation of biomass.

Question 16.
Name the country which generates maximum electricity using wind energy ?
Answer:
Germany produces maximum electricity using wind energy.

Question 17.
What should be the maximum wind speed to operate wind turbine?
Answer:
The maximum wind speed shall be 15 Km hr^-1.

Question 18.
How much power does a single photo voltaic cell produce ?
Answer:
The power output of a single solar photo voltaic cell varies between 1.0 to 1.5 w.

Question 19.
Name two semi conducting materials which are used to make solar cells.
Answer:
Solar cells are made of Silican (Si) and Gallium (Ga).

Question 20.
Between Petrol and Kerosene, which has a higher calortic value?
Answer:
Petrol (50 Kj g^-1) has a higher calorific value than Kereosene (48 Kj g^-1).

Question 21.
Name two devices in which solar energy is harnessed directly.
Answer:
Solar energy is harnessed directly in solar cookers and solar water heaters.

Numerical Problems :

Working fomula :

Calorific value of fuel :
Amount of heat energy liberated on burning of a fuel = (mass of fuel) × (Calorific value of fuel)

Solar constant :
Heat energy produced by incident solar radiation =(Solar constant) × (Area) × (time)
Where solar constant =1.4 kjm^-2 s^-1 = 14 kwm^-2

Examples 1: Calculate the energy released by a piece of wood of mass 10 kg when it is completely burnt. (The calorific value of wood is 17 Kjg^-1)
Answer :
Amount of heat energy liberated on burning a fuel (piece of wood)
= (mass of fuel) × (Calorific value of fuel)
= 17 × 10000 kj
[Mass of fuel, m = 10 kg
= 170000 kj
= 10000 g
Calorific value of fuel = 17 Kjg^-1 ]

Example 2 : The calorific value of a gas is 40 Kjg^-1. If a furnace contains 40 g gas in 40 second, calculate the power of the furnace.
Answer :
Gas consumed by the furnace is 40 second = 40 g
∴ Energy consumed by the furnace is 40 second
= 40 × 40 kj=1600 kj
∴ Power of the furnace = \(\frac{Energy}{ Time}\) = \(\frac{40 \times 40}{40}\) kjs^-1
= 40 kw