CBSE Class 10 Science Sources of Energy Assignment Set 03

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Question : What is the full from of OTEC 
a. Other traditional energy crisis
b. Ocean themed energy cooperative
c. Ocean thermal energy conversion
(d) Ocean thermal energy corporation
Answer : C
Explanation: Ocean thermal energy conversion is a process that can produce electricity by using the temperature difference between deep cold ocean water and warm tropical surface waters.
 
Question :  India exploded her first under ground nuclear device 
a. Pokhran
b. Kota
c. Ranchi
d. Jaipur
Answer : A
Explanation: Pokhran is a small town in district of Jaislmer(Rajasthan). Here India first time explanted nuclear power exercise. It was on May 18 1974.
 
Question :  A fuel would be regarded as ‘environment friendly’ if 
a. It produces large amount of ash
b. Its combustion products are non poisonous
c. Its combustion products are pollutant
d. Its calorific value is less
Answer : B
Explanation: If the products are poisonous then there will be a lot of pollution as a result of which everyone on the earth gets effects which inturn leads to the destruction of life. 
 
Question : The glass cover used in a solar cooker, help us to have the _________ effect in it. 
a. White house.
b. Black house
c. Blue house
d. Green house
Answer : D 
Explanation: The glass sheet in the solar cooker creates a greenhouse effect.
Glass sheet has a property that allows the infrared rays of shorter wavelength from the sun to get in the device but does not allow the IR rays of longer wavelength to leave the solar heating device.
 

Very Short Answers

Question : What type of energy is possessed by wind? 
Answer :  As wind is nothing but moving air, so it posses kinetic energy
 
Question : Name two dams whose construction was opposed by local people 
Answer :  Tehri Dam (Ganga river) , Sardar Sarovar Dam (Narmada river) are two dams whose construction was opposed by local people.

Question : Give two ways in which animal dung can be used as fuel. Which way is better and why?
Answer :  As dung cake and as Biogas.. Biogas is better because it spreads less pollution and has more calorific value.

Question : Write the drawback of energy obtained from fusion.
Answer :  The energy from fusion cannot be controlled.

Question : The wind velocity at three places A,B and C are 5Km/hr,15Km/hr,10Km/hr respectively. Which is the most suitable place for installing wind mill & why?
Answer : B, Maximum velocity required is 15km/h. At lower speed it will not work. At very high speed it may break the blades.

Question : What are two advantages of charcoal over wood as fuel?
Answer : High calorific value & pollution free

Question : How difference in temperature helps to harness energy from ocean?
Answer : The difference in temperature helps to obtain energy in ocean- thermal – energy conservation plants, which operate for temperature difference of 20о C or more. The warm surface water is used to boil a volatile liquid . The vapours of the liquid are used to run the turbine of generator , the cold water from the depth of the ocean is pumped up and condense vapour again to liquid.

Question : Mention any two reasons, why wood is not preferred as fuel.
Answer : (i) Burning wood causes pollution
-(ii)Excess use of wood would cause deforestation.

Question : Write two different ways of harnessing energy from ocean. 
Answer :  The two ways by which ocean energy can be harnessed are:
a. Wave energy.
b. Tidal energy.
 

Short Answers

Question : Why is biogas a better fuel than animal dung cakes? 
Answer :  Biogas is a better fuel than animal dung cakes because:
i. Burning of animal dung cake produces smoke which causes lot of pollution whereas biogas is a smokeless fuel.
ii. The calorific value of animal dung cake is much lower than that of biogas.
iii. Animal dung cakes leave residue after burning whereas biogas leaves no residue.

Question : In the given flow chart of energy conversion during hydroelectric power generation,fill in the blanks with appropriate answer

""CBSE-Class-10-Science-Sources-of-Energy-Assignment-Set-C

Answer : Dynamo.

Question : Consider two solar cooker, one covered with a plane glass plate and other kept open. Which of the two cooker would be more efficient and why?
Answer : Solar cooker with covered glass slab, as it will show green house effect.

Question : Give one reason how increasing depandance on nuclear power generation is a threat for future generation?
Answer : Radiation emitted during leakage can change the genetic arrangement or disposal to nuclear waste.

Question : Give two ways in which animal dung can be used as fuel. Which way is better and why?
Answer : As dung cake and as Biogas.. Biogas is better because it spreads less pollution and has more calorific value.

Question : The wind velocity at three places A,B and C are 5Km/hr,15Km/hr,10Km/hr respectively. Which is the most suitable place for installing wind mill & why?
Answer : B, Maximum velocity required is 15km/h. At lower speed it will not work. At very high speed it may break the blades.

Question : What are two advantages of charcoal over wood as fuel?
Answer : High calorific value & pollution free

Question : How difference in temperature helps to harness energy from ocean?
Answer : The difference in temperature helps to obtain energy in ocean- thermal – energy conservation plants, which operate for temperature difference of 20о C or more. The warm surface water is used to boil a volatile liquid . The vapours of the liquid are used to run the turbine of generator , the cold water from the depth of the ocean is pumped up and condense vapour again to liquid.

Question : Mention any two reasons, why wood is not preferred as fuel.
Answer : (i) Burning wood causes pollution
-(ii)Excess use of wood would cause deforestation.

Question : Write three reasons why construction of Tehri Dam on river Ganga and Sardar Sarovar project on river Narmada is opposed by local people and environmentalist?
Answer : (i) Rehabilitation problems, loss of agricultural land.
(ii) Disturbance of ecological balance.
(iii) Forming of green house gases due to decomposition of plant in water.

Question : Write three environmental consequences of the various source of energy we used?
Answer : Green house effect, improper use of natural resources, pollution.

Question : What is a role of fuel in everyday life ? 
Answer :  Fuels play very important role in our everyday life because we use several types of fuels for our different requirements. Theses are discussed below:
i. For domestic use : Fuels like wood, coal, kerosene, domestic gas, cow-dung, charcoal etc. are used in our homes for cooking food and other domestic heating purposes.
ii. For transport : Coal, diesel and petrol are used to run the transport. For example, petrol is used in running light vehicles such a scooters, motor-cycles, cars etc. Diesel oil is used in running heavy vehicles, such as trucks, buses, tractors, railway engines, tanks etc.
iii. In Industries : Fuels like coal, fuel oil or natural gas are used in industries to heat up boilers.
iv. To generate electricity : Fuels like coal or natural gas are used in thermal power plants to generate electricity.
v. As rocket fuel : Some special types of fuels such as hydrazine, liquid hydrogen, etc. are used in rockets. These types of fuels used in rockets are called propellants.
Thus, fuels play a pivotal role in our lives by helping us in different areas.
 
Question : Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answers. 
Answer :  Yes, sun is the ultimate source of energy. Directly or indirectly, all the forms of energy derived from solar energy.
i. Non-renewable sources of energy Fossil fuels like coal, petroleum and natural gas are formed due to burial of large plants and ancient creatures.
ii. Renewable sources of energy They are indirectly derived from solar energy such as:
a. Energy from flowing water Clouds are formed when water in Takes, rivers, seas, etc., evaporates due to solar energy. They bring rainfall and snow fall. 
b. Bio-energy Plants in the process of photosynthesis convert the solar energy into food (chemical energy). This food is consumed by animals.
c. Wind energy Wind arises due to uneven heating of the earth’s surface by the sun rays at two different adjoining places. Wind possesses kinetic energy.
d. Ocean thermal energy Sun is responsible for the temperature difference between the water at the surface and water at depth in seas and oceans.
e. Wave energy The waves are generated by strong winds (due to solar energy) blowing across the sea.
iii. Solar heating devices They derive their energy directly from solar energy and convert it into other usable forms of energy.
 

Long Answers

Question : What are hazards of incomplete combustio? 
Answer :  Hazards of Incomplete combustion :
Fuels contain a good amount of carbon. When combustion is complete, most of carbon gets converted into harmless carbon dioxide but when combustion is incomplete, the carbon does not burn properly resulting in following hazards :
a. Major portion of carbon gets converted into extremely poisonous carbon monoxide. Carbon monoxide pollutes the atmosphere and causes acute respiratory problems.
b. Sun emits a very large amount of ultraviolet rays which are very harmful to us.
These radiations are stopped by layer of ozone gas (O3) present between 50 to 80 km from earth. thus we are saved from harmful effect of ultraviolet rays. Carbon monoxide produced due to partially burnt carbon combines with ozone and gets converted to carbon dioxide.
CO + O3 → CO2 + O2
This damages ozone layer and hence exposes us to harmful of ultraviolet radiations. If the automobiles are not properly services and tuned, they produce a large amount of partially burnt carbon monoxide. This is the reason as to why the government stresses for periodical pollution tests.
c. During partial combustion some of the unburnt carbon passages into atmosphere in form of soot. There is not only sheer wastage of fuel but also pollutes atmosphere. 
 
 Question :  What is L.P.G.? Why is it called a good fuel? 
Answer :   The petroleum gas liquefied under pressure is called liquefied petroleum gas (L.P.G.) It consists mainly of butane with small amount of propane and ethane. This the domestic gas that we use. The gas used for domestic cooking purposes is called Liquefied Petroleum Gas (L.P.G.) because it is obtained from petroleum and it is liquefied by compression before filling in cylinders.
Uses of L.P.G.
The L.P.G. is mainly used for domestic heating purposes. It is obtained in cylinders.
When we turn the knob of the gas cylinder, the pressure is released resulting in decrease of pressure inside the cylinder so that highly volatile L.P.G. changes into gas.
The gas flows to the burner of the cooking stove. When ignited, the gas burns with a blue flame producing a lot of heat. This heat is used for cooking our food.
Advantages of L.P.G.
Liquid petroleum gas is considered to be a good fuel because of the following reasons :
i. L.P.G. has a high calorific value. Its calorific value is about 50 kJ/g. This means that when 1 gram of L.P.G. burns in a gas stove, it produces about 50 KJ of heat energy.
Therefore, it has higher efficiency as a fuel.
ii. It is very neat and clean domestic fuel. It burns with a smokeless flame and so does not cause pollution.
iii. It does not produce any poisonous gases on burning.
iv. L.P.G. is easy to handle and it is convenient to store.
v. It undergoes complete combustion. 
 
Question : a. Name the device used to convert
i. Solar energy in to heat and
ii. solar energy in to electricity.
b. Explain the working of windmill
Answer :
a. i. Solar cooker
ii. Solar cell.
b. When the wind blows with a minimum speed of 15km/hr, the kinetic energy of the wind is used to rotate the blades of wind mill. The mechanical energy of the rotating blades is used to rotate the armature of the generator and generator in turn produces electricity.

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CBSE Class 10 Science Assignments for Chapter 14 Sources Of Energy

Revision Assignment: Chapter 14 Sources Of Energy (CBSE)

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