CBSE Solutions for Class 10 English

જવાબ : Kinetic energy.

જવાબ : The region where large number of wind mills are erected to produce electricity is called wind energy farm.

જવાબ : The sun,
The wind.

જવાબ : The sources of energy which are continuously supplied by nature. For example, the sun, the wind.

જવાબ : Nitrogen and phosphorus, on Wind energy

જવાબ : CNG – Non-renewable
Hydrogen – Renewable.

જવાબ : Methane gas and hydrogen gas.

જવાબ : Methane gas. 75% of total volume.

જવાબ : Biogas is a mixture of four gases namely methane, carbon dioxide, hydrogen and hydrogen sulphide.

જવાબ : Anaerobic micro-organisms.

જવાબ : Charcoal.

જવાબ : Charcoal is obtained from wood by heating the wood in the absence of air. This process is known as destructive distillation of wood.

જવાબ : Plants and animals waste material which can be used as fuel is called biomass.

જવાબ : Depletion of forests means deforestation which is responsible for green house gases such as CO2 and methane. on Biogas

જવાબ : Since hydro power is derived from the renewable source of energy i.e., sun, so it is also a renewable source of energy.

જવાબ : 1.    Sulphur dioxide
2.    Nitrogen dioxide.

જવાબ : CO2, SO2.

જવાબ : CNG stands for “compressed Natural Gas”.

જવાબ : The main constituent of CNG is methane.

જવાબ : Thermal power plant produces electricity by burning fossil fuels.

જવાબ : Disadvantage : The burning of coal or oil in a thermal power plant causes environmental pollution and global warming.

જવાબ : The main constitutent of “LPG” is butane.

જવાબ : LPG stands for “Liquid Petroleum Gas”.

જવાબ : More use of fossil fuels for fulfilling the increasing demand for energy is polluting the air, which is a great health hazard.

જવાબ : Coal and petroleum.

જવાબ : 1.    Coal,
2.    Petroleum.

જવાબ : Fossil fuels like coal and petroleum are exhaustible sources of energy. The estimated reserves of these fuels are said to last us for about another 200 years, while it takes millions of years for these to be formed.

જવાબ : (i) Energy derived from biomass is a renewable source of energy because waste products are continuously produced. Plants and trees are also grown at reasonable intervals.
(ii) The energy derived from flowing water, wind, sun and ocean are renewable sources because these sources can be harnessed into energy so long as the present solar system exists.

જવાબ : Hydrogen is cleaner fuel than CNG. This is because the burning of hydrogen produces only water, which is totally harmless. On the other hand, burning of CNG produces carbon dioxide gas and water. The carbon dioxide can produce greenhouse effect in the atmosphere and lead to the excessive heating of the environment in long run.

જવાબ : No source of energy can be pollution free because even if it is clean, its assembly could have caused some environmental damage.

જવાબ : A concave mirror would be best suited in a solar cooker because it focuses the sunlight in a very small area of the solar cooker and a high temperature is produced in it which is sufficient to cook the food.

જવાબ : We are looking at alternate sources of energy because of the following reasons.
•    The fossil fuels and nuclear fuels on the earth are limited which may not last for long.
•    The undesirable effects of pollution, both from the burning of fossil fuels and from the radioactive nuclear wastes of nuclear power plants are creating threat to our environment.

જવાબ : I would prefer to use cooking gas like LPG. It fulfils many of the criteria of a good fuel like its ignition temperature, good calorific value and non-polluting characteristics.

જવાબ : Advantages:
The heat source for a solar cooker is sunlight. It is a clean renewable and inexhaustible source of energy. As its availability is unlimited, it will be pocket-friendly.
Disadvantages:
It doesn’t work on a cloudy day.

જવાબ : Fossil fuels are obtained from the earth’s crust as they are the remains of the dead plants and animals. They are similar to coal and petroleum and readily available for use. These are non-renewable source of energy and cannot be replenished.
Whereas solar energy is abundant in nature and can be replenished.

જવાબ : Hydrogen gas is cleaner than CNG as CNG contains hydrocarbons. Carbon is a form of pollutant in CNG. On the other hand, hydrogen is waste-free and the fusion of hydrogen does not produce any waste. Hence, hydrogen as a rocket fuel is cleaner than the CNG.

જવાબ : No source of energy can be completely pollution-free. But solar cells are considered to be pollution-free. But their manufacturing may cause environmental damage. In case of nuclear energy, the waste produced after fusion is zero. But the wastes that are produced during fission are hazardous. Hence, no source of energy is pollution-free.

જવાબ : Following are the advantages of nuclear energy:
•    Amount of energy produced per unit mass is large
•    As it does not produce any pollutants, it is clean
•    Fission of 1 atom of uranium produces 10 million times the energy that is obtained by burning 1 atom of carbon

જવાબ : Geothermal energy can be defined as the energy that is obtained from the earth. The energy can be obtained from the hot spots that are formed when the molten rocks at the core of the earth are pushed to the earth’s crust. Hot springs are used for the production of electricity in the geothermal power plants.

જવાબ : For a solar cooker the heat source is sunlight for heating and cooking. The reason why a mirror is used is to reflect and focus the sunlight at one point. So a concave mirror can be used in a solar cooker, as it focuses all the sunlight at one point resulting in increase in temperature, thereby heating and cooking the food.

જવાબ : The reason why we are looking at alternate sources of energy is because the fossil fuels are non-renewable sources of energy, i.e. they are not available in large quantities and cannot be replenished. Fossil fuels will get exhausted if their consumption is not controlled. Therefore, it is better to switch to alternate source of energy.

જવાબ : For heating and cooking, natural gas can be used for the below given reasons:
•    It is easy to use
•    It is easily available
•    Easy transportation
•    It does not produce huge amount of smoke when burnt
•    It is highly inflammable.

જવાબ : A fuel is said to be good when it is easily available and when it produces a large amount of heat energy when burnt.

જવાબ : A good source of energy has the following properties:
•    Be economical
•    Easy storage and transportation
•    Easy availability
•    Work done per unit volume or mass should be large.

જવાબ : black

જવાબ : Hot spots

જવાબ : windmill

જવાબ : Anaerobic microorganisms

જવાબ : non-renewable

જવાબ : fossil fuels

જવાબ : Disadvantages of Nuclear Fission Energy over the Fossil Fuel Energy

• Nuclear fission causes more serious pollution problem than the burning of fossil fuel. The radiation emitted during nuclear fission are very harmful. They cause dangerous diseases like cancer, leukemia and sterility.
• The biggest problem of using nuclear fission energy is the safe disposal of nuclear waste. Nuclear waste continues to emit harmful nuclear radiation. No method has been evolved for the complete elimination of the nuclear waste. But no such problem is faced in the disposal of the fossil fuel waste. For example, burning of coal give rise to ash which can be thrown in the fields. That is why, it is advised not to use nuclear fission for the production of energy on very large scale.

જવાબ : Geothermal energy and nuclear energy are different from the bio-mass energy, wind energy and ocean thermal energy. This is because, bio-mass energy, wind energy and ocean thermal energy are derived from a single source of energy, that is the sun. On the other hand, geothermal and nuclear energies are not derived from the sun. Based on Nuclear energy

જવાબ : The warm surface water of ocean is used to boil liquid like ammonia or chlorofluoro carbon in OTEC power plant. The vapours of this liquid at high pressure rotates the turbine of a generator to produce electricity. The dead steam is again converted into liquid by the cold water pumped up from the deep ocean. This process is repreated continuously to convert ocean thermal energy into electrical energy.

જવાબ :

1. Tidal energy,
2. Ocean waves energy
3. Ocean thermal energy.

જવાબ : A solar cooker covered by a plane glass slab will be more efficient.
This is because glass slab does not allow the heat radiation to escape from the solar cooker and hence the temperature of the solar cooker covered with glass slab increases more than the temperature of the solar cooker which is left open.

જવાબ : (a) Plane mirror reflects solar light to fall on the glass sheet of the solar cooker. Plane glass plate does not
allow the infrared or heat radiation entered in the box to go out side the box. Thus, the box becomes hot. The phenomenon is known as green house effect.
(b) Solar energy evaporates water in rivers, lakes and oceans. These water vapours are converted into clouds (K.E. + P.E.). The clouds give rise to rain and hence water flows in rivers. Thus, energy of flowing water in the form of kinetic energy is the indirect form of solar energy.
(c) Nuclear fusion reaction gives rise to energy which is pollution-free.

જવાબ :

1. We cannot depend upon wind energy as it is available only when air is in motion. The appliances or machines operating with wind energy stop working as soon as wind stops. The minimum speed of wind to operate generator to produce electricity is about 15 km/h. As soon as the speed of the wind becomes less than 15 km/h, the generator stops working.
2. There are certain regions where wind is not available, so the use of wind energy is limited to certain places where wind is in plenty and blows most of the time.
3. Wind energy is not sufficient to operate very heavy machines.
4. Wind energy cannot be used to operate all types of machines.
5. Wind mills are usually broken during storms and hence lot of money is spent for the maintenance of a wind energy form.

જવાબ : This is because

1. Deforestation (i.e., cutting of trees in large number) causes many problems like floods, erosion of fertile land and environmental imbalance.
2. Replenishment of forests takes long time and as such wood cannot be available to supply continuous energy.

જવાબ : The heat energy stored in the hot spots of the earth’s crust is called geo-thermal energy.
For advantages:

1. Geo-thermal energy can be converted continuously into electricity for 24 hours in a day throughout the year.
2. Geo-thermal energy causes no pollution, so it is environment friendly.
3. The cost of converting geo-thermal energy into electricity is very less.

જવાબ : Dams are helpful to :

• control floods over rivers.
• generate hydro electricity.
• irrigate agriculture land.
• develop water sports for recreation
• develop fishing zones.

જવાબ : Disadvantages of Hydroelectric Power :

1. Hydroelectric power is generated only near the rivers having water throughout the year. This electric power has to be carried to the sub­stations for distribution to the houses and factories situated far off from the sites of hydro electric power stations. This is done through the transmission wires, so lot of money is to be spent on this process.
2. A large area of fertile land is submerged at the site of the dam constructed for tapping energy from the flowing water.
3. A large number of people residing near the site of a dam are dislocated. So, a lot of problems are to be faced in rehabilitating this population. That is why, there is a lot of opposition by the people around the site of dam for the construction of dam.
4. A large number of plants and wild life in the area of the dam are submerged in water. So, a large variety of flora (plants) and fauna (animals) is destroyed.
5. Hydroelectric dams cannot be constructed everywhere. They are constructed mostly in hilly areas.

જવાબ :

1. A large area of fertile land is submerged in water at the site of the dam.
2. A large number of people residing near the site of dam are dislocated. Hence, lot of problems are to be faced in rehabilitating this population.
3. A large number of plants and wild life in the area of the dam is submerged in water.

જવાબ : Advantages of Hydroelectric Power

• Hydroelectric power is pollution free.
• Fiydroelectric power- is dependable source of energy.
• Lot of water is available in rivers, so the hydroelectric power is available free of cost. Money is spent only to construct dams and power stations.

જવાબ : For fossil fuels: The combustible substance formed from the dead remains of the animals and plants which were buried deep under the surface of the earth over millions of years is called fossil fuel.
Gases produced due to the burning of fossil fuels react with water vapours in air to produce acids like carbonic acid, sulphuric acid and nitric acid. These acids come down to earth with rain known as acid rain.

જવાબ : Advantages of using solar cooker :

• The use of solar cooker for cooking food saves precious fuels like coal, kerosene and LPG.
• The use of solar cooker does not produce smoke due to which it does not pollute air.
• When food is cooked in solar cooker, its nutrients do not get destroyed. This is because in a solar cooker, food is cooked at a comparatively lower temperature.
• In a solar cooker, up to four food items can be cooked at the same time.

• The solar cooker cannot be used to cook food during night because sunshine is not available at that time.
• If the day sky is covered with clouds, even then solar cooker cannot be used to cook food.
• The direction of reflector of solar cooker has to be changed from time-to-time to keep it facing the sun.
  Sources of Energy
• The box-type solar cooker cannot be used for baking (making chappattis, etc.) or for frying.
  The places that receive rain most of the year or where the sky remains cloudy, the solar cooker has limited utility.

જવાબ : (a) Renewable sources : The sources of energy which are being produced continuously in nature and are inexhaustible, are called renewable sources of energy. The energy derived from flowing water, wind, tides, ocean waves, or wood are examples of energy from such sources.
Non-renewable sources : These sources are produced over million of years under special conditions. Once consumed, these are not replaceable for a very long time. Fossil fuels like coal, petroleum and natural gas are non-renewable sources.
(b) Exhaustible sources are non-renewable sources, while inexhaustible sources are renewable sources.
Yes, the options given in (a) and (b) are the same.

જવાબ :

જવાબ :

જવાબ : Energy stored as heat in certain regions of the earth (called hot spots) is called geothermal energy. Hot spots are the locations below earth’s crust where upward moving magma gets collected due to geological changes. When underground water comes in contact with the hot spots, steam is generated. This steam is utilised to generate electricity using pipes and turbines. Sometimes hot water from the hot spot finds outlet at the surface. Such outlets are called hot springs.

જવાબ : The advantages of nuclear energy are that :

1. It produces a large amount of useful energy from a very small amount of a nuclear fuel (like uranium-235).
2. Once the nuclear fuel (like uranium-235) is loaded into the reactor, the nuclear power plant can go on producing electricity for two to three years at a stretch. There is no need for putting in nuclear fuel again and again.
3. It does not produce gases like carbon dioxide which contributes to greenhouse effect or sulphur dioxide which causes acid rain.

જવાબ : The energy from the oceans can be obtained mainly in three forms. These are
(i) tidal energy
(ii) wave energy and
(iii) ocean thermal energy

• Limitations of Tidal Energy :
  (i) There are very few sites around the world which are suitable for building tidal dams.
  (ii) The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.
• Limitations of wave energy : The movement of ocean waves is associated with kinetic energy. Such sites in the world are limited where the waves strike the shore lines with sufficient power.
• Limitations of ocean thermal energy : NCERT Solutions for Class 10 Science Chapter 14 Sources of EnergyTo convert ocean thermal energy into electricity, a temperature difference of 20°C (or more) between the surface water of ocean and deeper water is needed for operating OTEC power plants. This involves high cost.

જવાબ : Industrialization demands for more energy and to fulfil these demands fossil fuels are used as they are readily available. Due to their harsh usage, it has an impact on the environment. Too much exploitation of fossil fuels has led to greenhouse effect resulting in global warming.

જવાબ : a) Renewable and non-renewable:
Renewable energy sources are those which replenish on their own and are easily available in nature. Like solar energy, tidal energy, wind energy, bio-mass.

જવાબ :

• a) The wind: Wind energy is trapped using windmills. One of the limitations of the wind energy is that the windmills requires a speed more than 15 km/h to generate electricity. And the number of windmills will be more to cover a huge area.
• b) Waves: In order to extract energy from the waves, very strong ocean waves are needed.
• c) Tides: In order to extract energy from the tides, the sun, the moon and the earth should be in a straight alignment and the tides should be very strong.

જવાબ : Bio-mass is obtained from the dead plants and animals. It is a renewable source of energy. Examples of bio-mass sources of energies are wood, gobar-gas.

જવાબ : Following are the two sources of energy that are exhaustible:

• Wood: The source of wood are forests. Due to deforestation the number of forests are reducing. We know that it takes years to grow forest. If the rate of deforestation increases, the availability of wood will decrease. Hence, wood is an exhaustible source of energy.
• Coal: The source of coal is from the dead remains of the plants and animals that remained buried for years. Industrialization has increased the demand for coal and it cannot be replenished. Hence, coal is also an exhaustible source of energy.

જવાબ : Following are the two sources of energy that are renewable:

• Wind: Wind energy is obtained from the air which is blowing at a high speed. Wind energy is trapped using windmills so as to generate electricity. Blowing of air is dependent on uneven heating of the earth. Since the heating of the earth is forever, wind availability will also be forever.
• Sun: The energy obtained from the sun is known as solar energy. It is produced by the fusion of hydrogen into helium, fusion of helium into other heavy metals and it continues. A large amount of hydrogen and helium is available in the sun which will never be exhausted. Hence, solar energy is renewable source of energy.

જવાબ : The different forms of energy that can be obtained from the ocean are tidal energy, wave energy and ocean thermal energy. Following are the limitations of the energy obtained from ocean:

• The relative positioning of the earth, the sun and the moon has an impact on the tidal energy.
• For the conversion of tidal energy into electricity, high dams are required.
• To obtain electricity from wave energy, very strong waves are required.
• For trapping the ocean thermal energy, there should be a temperature difference of more than 20°C between hot surface water and the cold water at a depth.

જવાબ : Following are the disadvantages of fossil fuels:

• Fossil fuels like coal and petroleum results in air pollution as there is release of huge amount of pollutants.
• Gases such as carbon dioxide is released when a fossil fuel is burnt, which causes global warming.
• Soil fertility and potable water is affected by the oxides of carbon, nitrogen, sulphur, etc. that are released from fossil fuels.

જવાબ : In olden days, wind energy was trapped used windmills to do mechanical works like lifting or drawing water from a well. But these days, windmills are used to generate electricity. The kinetic energy of wind is trapped and converted into electricity with the help of rotatory motion of the blades, which turns the turbine of the electric generator to produce electricity.

જવાબ :