Class 10 Science Chapter 14 Board Questions

Class 10 Science Chapter 14 Board Questions of Sources of Energy. It is the collections of questions of 1 mark, 2 marks, 3 marks and 5 marks which are asked in CBSE board examination in last 10 years. Important questions from last ten years CBSE board papers and all the questions from last 5 years papers are given with answers here. These questions are useful for the preparation of board exams as well as school tests. 1 mark questions are answered in one sentence or one word whereas 2 and 3 marks questions are described as per the need of questions. 5 marks questions are answered point to point.

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Class 10 Science Chapter 14 Board Questions for Exams

Class: 10Science
Chapter: 14Board Questions with Answers

Class 10 Science Chapter 14 Board Questions for Practice

Class 10 Science Chapter 14 Board Questions for exams practice. All the important questions from last ten years CBSE Board papers and all the questions from last 5 years CBSE exams papers are given below with answers. Answers of the questions are taken from NCERT Textbooks only.

10th Science Chapter 14 Board Questions Set – 1 (1 Mark)

Name the reaction responsible for large energy production in the sun. [CBSE 2012]

Nuclear fusion.

List two nutrients that the slurry left behind in the biogas plant contain. [CBSE 2011]

Nitrogen and phosphorous.

Biogas is also known as gobar gas. Justify. [CBSE 2011]

Starting material for biogas is mainly cow dung. So it is also known as gobar gas.

List any two advantage of burning charcoal over burning wood. [CBSE 2011]

Advantages of burning charcoal over burning wood.
(i) It has high calorific value.
(ii) It produce less smoke and less ash.

List two practical uses of biogas in rural areas. [CBSE 2011]

Practical uses of bio-gas in rural areas.
(i) It is an excellent fuel which burns without smoke with high heating capacity.
(ii) It is also used for lightening.

10th Science Chapter 14 Board Questions Set – 2 (1 Mark)

What is the minimum speed of wind to run a windmill to maintain the necessary speed of turbine of an electric generator? [CBSE 2008]

15 km/h

How is nuclear energy generated during nuclear fusion? [CBSE 2008]

In nuclear fusion the difference in mass, between the original nucleus and a product nucleus gets converted to energy as per Einstein’s mass energy equation.

How has the traditional use of wind energy been modified for our convenience? [CBSE 2008]

With the help of wind energy rotatory motion of windmill is utilised to
(i) lift water from a well or
(ii) turn the turbine of electric generator that generate electricity.

Name the major sources of energy that are largely fulfils the growing demand of energy in our country. [CBSE 2011]

Fossil fuels like coal and petroleum.

State the ultimate sources of energy of fossil fuels. [CBSE 2012]

Sun.

Question: What is a fuel? [CBSE 2010, 2012]
Answer: Fuel is that which produce heat energy on burning example firewood, charcoal, coal, petroleum, cooking gas etc.

10th Science Chapter 14 Board Questions Set – 3 (1 Mark)

The use of dry wood as domestic fuel is not considered as good. State two reasons for it. [CBSE 2011]

(i) Dry wood produces a lot of smoke on burning which cause air pollution.
(ii) It is a non-renewable sources and its calorific value is not high.

What are the two disadvantages of burning fossil fuels?

(i) Burning of fossil fuels produce smoke which cause air pollution. [CBSE 2014]
(ii) Oxides of carbon, nitrogen and sulphur released on burning fossil fuels cause green house effect as well as acid rain.

Name any two renewable source of energy? [CBSE 2012]

Solar energy, wind energy, ocean wave energy, bio mass-energy etc.

Name any two source of energy which are pollution free. [CBSE 2011]

Solar energy and wind energy.

Name two alternative source of energy. [CBSE 2011]

Bio-gas, solar energy and ocean energy.

10th Science Chapter 14 Board Questions Set – 4 (1 Mark)

Name the reaction responsible for large energy production in the sun. [CBSE 2012]

Nuclear fusion reaction taking place in the interior of the sun.

In solar cooker, why is its inner surface blackened? [CBSE 2010]

Because a black surface easily absorbs solar radiation incident on it.

Why is the solar cooker box covered with a plane glass plate? [CBSE 2011]

The glass plate allows solar radiation to pass through it but the heat radiation from inside are not allowed to escape by the glass plate. Thus it helps in maintaining temperature inside solar cooker high.

Mention the main purpose of using a plane mirror in solar cookers. [CBSE 2010, 2013]

The plane mirror reflects sun rays so that these reflects rays fall on the item to be cooked.

Identify the part of a solar cooker that produces greenhouse effect. [CBSE 2016]

The plane glass plate cover of a solar cooker produce greenhouse effect.

Question: List two main advantages associated with solar cells. [CBSE 2010]
Answer:
(i) They have no moving parts and require little maintenance.
(ii) They can be set up even in remote areas.

10th Science Chapter 14 Board Questions Set – 5 (1 Mark)

Name the device that directly converts solar energy to electric energy. [CBSE 2010, 2011]

A solar cell.

Name chief compound of solar cells. Which energy conversion takes place in a solar cell? [CBSE 2010, 2012]

Silicon is the chief component of solar cell. A solar cell converts solar energy into electrical energy.

Name any two elements that are used in fabricating solar cells. [CBSE 2019]

Silicon and gallium.

What is wind energy? [CBSE 2010]

The kinetic energy possessed by air due to its motion is called wind energy.

Mention the two factors that causes wind to blow. [CBSE 2015]

Wind is caused by unequal heating of land mass and water bodies by solar radiation.

10th Science Chapter 14 Board Questions Set – 6 (1 Mark)

What is the minimum wind velocity required for obtaining electric power with a windmill generator? [CBSE 2007, 2011, 2014, 2015, 2016]

15 km/h

How has the traditional use of wind energy been modified for our convenience? [CBSE 2010, 2011]

The rotatory motion of the traditional windmill is used to turn the turbine of the electrical generator so that wind energy is converted into electrical energy.

Write the energy conversion that takes place in hydropower plant. [CBSE 2018]

In a hydropower plant potential energy of water stored in a dam is converted into electrical energy.

How does construction of dams across the river get linked with the production of greenhouse gases? [CBSE 2010, 2011]

The vegetation of submerged areas of forests rots under anaerobic conditions and gives to methane which is a greenhouse gas.

List any one harm that is caused to environment by hydropower plant. [CBSE 2013]

Large eco systems are destroyed when submerged under the water in dams constructed for hydropower plants.

Question: What is a solar panel? [CBSE 2011]
Answer: A solar panel consists of a large number of solar cells combined together so that it can deliver enough electricity for practical use.

10th Science Chapter 14 Board Questions Set – 7 (1 Mark)

What type of energy is possessed by huge waves near the sea shore? [CBSE 2010]

The tidal energy

Write two different ways of harnessing energy from ocean. [CBSE 2010, 2012, 2014]

Tidal energy wave energy and ocean thermal energy are the different ways of harnessing energy from ocean.

Give the composition of the slurry fed into the digestion of a gobar gas plant. [CBSE 2011]

Slurry consist of mixture of bio-mass and water.

What is a bio-mass? [CBSE 2010, 2012]

Remains of dead animals, animal waste, agriculture wastes etc., constitute bio-mass example cow dung, sewage, husk, vegetable waste etc.

What is bio-gas? [CBSE 2012]

Gases produced by anaerobic decomposition of plant and animal wastes are called bio-gas.

10th Science Chapter 14 Board Questions Set – 8 (1 Mark)

Which one of the following gases is the major constituent of bio-gas? Carbon monoxide, hydrogen, methane, carbon dioxide. [CBSE 2010, 2013]

Methane gas (about 75 %).

Write the percentage of methane in bio-gas. [CBSE 2016]

75% of bio-gas is methane.

What is the use of the slurry left behind in the digester of a bio-gas plant? Give reason [CBSE 2012]

The slurry left behind in the digester is used as a manure.

Name any two nutrient that the spent slurry has in a bio-gas plant. [CBSE 2011, 2019]

Nitrogen and phosphorous are two nutrient present in the spent slurry.

Why is bio-gas considered an excellent fuel? [CBSE 2019]

Bio-gas is an excellent fuel because it burns without smoke, leaves no residue ash and its heating capacity is high.

Question: Define the process of nuclear fission. [CBSE 2007, 2015]
Answer: Splitting up of a nucleus of uranium when bombarded by neutron, into two lighter nuclei along with release of a large amount of energy is called nuclear fission.

10th Science Chapter 14 Board Questions Set – 9 (2 Marks)

Biogas is considered to be a boon to a farmer. Give reasons. [CBSE 2011]

(i) Source of excellent manure, rich in nitrogen and phosphorus which can be obtained from the biogas plant in addition to biogas.
(ii) It provides the safe, efficient and profitable disposal method for bio-waste and sewage material.

Give two advantages of nuclear energy. [CBSE 2011]

Advantages of nuclear energy
(i) A small amount of nuclear fuel releases a tremendous amount of nuclear energy.
(ii) Once the nuclear fuel is loaded in the nuclear reactor, then it can operate for two to three years without any need of refueling.

What is a solar cell panel? Mention any three of its application. [CBSE 2011]

Solar cell panel: A large number of solar cells combined in an arrangement is called solar cell panel.
Application of solar cell panel
It provides the electric power for the
(i) Working of artificial satellites stationed in outer space.
(ii) Running of irrigation water pump by the farmers in rural areas.
(iii) Street lightning in remote areas.

Mention any four limitations in the harnessing wind energy [CBSE 2010]

Limitations in harnessing wind energy
(i) Speed of wind is not available at all time and at all places.
(ii) To establish the wind energy farm a large area of land is needed.
(iii) Speed of wing should be higher than 15 km/h to harness the wind energy.
(iv) Construction of wind-mill and its installation is very expensive.

What happen when wood is burnt in a limited supply of oxygen? Name the residue left behind after the reaction and state two advantages of using this residue as a fuel over wood. [CBSE 2010]

When wood is burnt in a limited supply of oxygen, volatile materials present in it get removed and its collected to get wood tar. Wood gas is collected.
The residue left behind after the reaction is known as charcoal.
Advantages of using charcoal as a fuel over wood
(i) Burning of charcoal does not produce any type of smoke. On the other hand, wood produces a lot of smoke on burning.
(ii) Charcoal produces more heat than wood.

Question: Suggest any two reasons which make the large scale usage of nuclear energy prohibitive. [CBSE 2011]
Answer: High cost of installation of a nuclear power plant and problem of safe disposal of nuclear waste are two main reasons.

10th Science Chapter 14 Board Questions Set – 10 (2 Marks)

Name four gases commonly present in biogas. State two advantages of using this gas over fossil fuels. [CBSE 2010]

Methane, carbon dioxide, biogas over fossil fuels
Advantages of using biogas over fossils fuels
(i) Biogas burns without smoke, leaves no residue unlike coal.
(ii) Biogas is cheaper as compound to fossils fuels.

How are the waste produces in nuclear power plants different from those produced in a thermal power plant? What happens to the waste of a nuclei power plant? [CBSE 2010]

The waste obtained from nuclear power plants are highly radioactive in nature which emits harmful radiation whereas waste produced in a thermal power plant is non-radioactive.
Management of nuclear waste
(i) Some products of nuclear waste are buried in sealed steel/lead containers for a long term storage, buried under the ground or dumped in a vacated coal mines.
(ii) Other waste products transforms into less harmful products or to products with a shorter half-life.

Out of the two solar cookers, one was covered with a plane glass slab and the other left upon. Which of the two solar cookers will be more efficient and why? [CBSE 2009, 2011]

The solar cooker which was covered with a plane glass slab will be more efficient. The glass lid allows the heat radiations from sun to enter the solar cooker but does not allow the reflected heat radiation to escape or go outside the box. Thus heat trapped inside the box increases the temperature. Glass lid also reduces heat loss due to reflection.

Why are many thermal power plants set up near coal or oil fields? [CBSE 2009]

Many thermal power plants are set up near coal or oil fields:
(i) to ensure continuous supply of coal or oil without any delay.
(ii) in order to minimise transportation cost, and
(iii) transmission of electricity is more efficient than transporting coal or oil over the same distances.

(a) Name two elements which can be used for generation of electricity in a nuclear power plant. (b) Why many nuclear power plants could not be installed in our country? Give two reasons. [CBSE 2009]

(a) Uranium-235 and Plutonium-239.
(b) (i)less availability of nuclear fuel in the country.
(ii) the construction of nuclear power plants and power generation cost are greater than the other manufactured sources of energy.

Question: How does bio-gas plant help to reduce the problem of pollution? [CBSE 2011]
Answer: In a bio-gas plant huge quantity of bio waste and sewage is used in a safe and efficient manner. Thus it helps in reducing pollution.

10th Science Chapter 14 Board Questions Set – 11 (2 Marks)
In a solar cooker, the following arrangements are made. Write one function of each arrangement. (a) The box is made of insulating material such as plastic or wood. (b) The inner walls of the box are painted black. (c) The box is covered with a transparent glass sheet. (d) A plane mirror is hinged at an angle at the top of the box. [CBSE 2009]

(a) To avoid loss of heat from solar cooker to the surroundings.
(b) Black surface absorbs more heat radiations of incident energy.
(c) Transparent glass sheet does not allow the reflected heat radiation to go outside the box.
(d) To increase the amount of solar energy incident on the transparent glass sheet.

Describe how hydro energy can be converted into electrical energy. Write any two limitations of hydro energy. [CBSE 2009]

Conversion of hydro energy into electrical energy
(i) High rise dams are constructed on the river to obstruct the flow of water to collect it at a suitable height.
(ii) The stored water has a lot of potential energy.
(iii) The water forms a suitable height is allowed to fall on the blades of a turbine located at the bottom of a dam through a pipe.
(iv) Kinetic energy of flowing water rotates the turbine rapidly.
(v) Rotation of turbine helps the armature coil of generator to rotate rapidly in the magnetic field.
(vi) Hydroelectricity is generated.
Limitations of hydro energy.
(a) All rivers sites are not suitable for construction of dams.
(b) Large ecosystems are destroyed when submerged under the water in dam.

How is energy generated in a nuclear fission reaction? Why is the large scale use of nuclear energy prohibitive? [CBSE 2008]

Energy generated in nuclear fission reaction- According to Einstein’s Mass energy relation, the lost mass between the sum of masses of disintegrated nucleus and original nucleus in nuclear fission reaction reappears in the form of tremendous amount of energy.
Large scale use of nuclear energy is prohibited because
(i) improper nuclear-waste strong and disposal results in environment contamination.
(ii) of high cost of installation of a nuclear power plant.
(iii) of limited availability of uranium
(iv) of risk of accidental leakage of nuclear radiation due to some natural or manmade causes.

List any four characteristics of biogas on account of which it is considered an ideal fuel. [CBSE 2008, 2016]

Biogas as an ideal fuel
(i) It is an environment friendly fuel as it lowers the greenhouse effect.
(ii) Its heating capacity is high i.e. it has high calorific value.
(iii) It burns without smoke, leaves no residue, therefore causes no atmospheric pollution.
(iv) It can be produced anywhere with less production cost and does not involve any running cost.

Name the type of nuclear reaction by which the Sun produces its energy. List two conditions which are present at the center of the sun responsible for this reaction. [CBSE 2006]

Nuclear fusion reaction
Conditions
(i) Presence of hydrogen.
(ii) High temperature (10107 k ) and millions of Pascal’s of pressure.

Question: Name any two nuclear fuels used for the purpose of nuclear fission. [CBSE 2014, 2016]
Answer: Uranium and plutonium.

10th Science Chapter 14 Board Questions Set – 12 (3 Marks)
(a) List in tabular form two major difference between renewable and non-renewable sources of energy. (b) Why fossil fuels are classified as non-renewable sources of energy? [CBSE 2010, 2012, 2013, 2016]

(a) Renewable source of energy:
(i) These are energy sources which are inexhaustible can be replenished and can be used to produce energy again and again.
(ii) Solar energy, energy of flowing water, wind energy are renewable source of energy.
Non-renewable:
(i) These are the energy sources which are exhaustible i.e., cannot be replenished after being once consumed.
(ii) Fossil fuels example coal, petroleum, natural gas and wood are non-renewable source of energy.
(b) Fossil fuels were formed due to certain very slow changes occurring inside the earth under special circumstances spread over millions of years. Since these conditions are not prevailing now it is not possible to replenish the amount of fossil fuels being consumed. Hence these are classified as non-renewable sources of energy.

What are fossil fuels? List four disadvantages of burning fossil fuels. [CBSE 2010, 2011, 2012]

Fossil fuels are fossil remain produced by the decay of plants and animals that were buried in the earth millions of year ago. Coal and petroleum are fossil fuels.
There are following disadvantage of fossil fuels:
(i) Burning of coal and petroleum causes air pollution.
(ii) Acidic oxides like oxides of carbon, nitrogen and sulphur are released on burning fossil fuels. These oxides lead to acid rains which adversely affect our water and soil resources.
(iii) Carbon dioxide gas also causes greenhouse effect in atmosphere.
(iv) Fossils fuels are non-renewable sources of energy.

State in brief the processing of harnessing kinetic energy of the wind to do work. Mention limitation of harnessing wind energy on a large scale. [CBSE 2010, 2011]

The kinetic energy of the wind is utilised in running windmills. A windmill may do mechanical work like pumping out water or grinding food grains. Now a day windmills are used to run turbines of electric generators and thereby producing electrical energy.
The following are the limitation of harnessing wind energy on a large scale:
(i) Wind energy farms can be established at those places only, where wind blows from the greater part of a year.
(ii) For wind energy the wind speed should be higher than 15km/h.
(iii) A wind farms require large area and initial cost of establishment of wind farms is high.
(iv) It require a higher level of maintenance because the tower and blades are exposed to rain, sun, storm etc.

(a) What do you mean by alternative source of energy? (b) How is wind energy converted into electrical energy? [CBSE 2010, 2013]

(a) Those renewable sources of energy which were previously not being used conventionally and which can be employed now are known as alternative sources of energy. Ocean energy, bio-energy and wind energy are some examples of alternative sources of energy.
(b) Windmill structure are similar to a large electric fan erected at a suitable height. In fast wind the windmill begins to rotate. The rotatory motion of the windmill is used to turn the turbine of the electric generator so as to produce electric energy.

What is meant by the wind farms? Write one of its practical application. Give any two limitations of using wind energy. [CBSE 2012]

A wind energy farms consist of a number of windmill erected over a large area such that output of all these windmills is coupled together. A wind energy farm is a renewable sources of energy generating electricity on a commercial scale.
The following are the limitation of harnessing wind energy on a large scale:
(i) Wind energy farms can be established at those places only, where wind blows from the greater part of a year.
(ii) For wind energy the wind speed should be higher than 15km/h.

Question: Write the full form of CNG. [CBSE 2011]
Answer: Compressed Natural Gas.

10th Science Chapter 14 Board Questions Set – 13 (3 Marks)
(a) State the energy transformation take place at hydropower plants. (b) Why is energy of water flowing in a river considered to be an indirect form of solar energy. [CBSE 2016]

(a) In a hydropower plant the potential energy of water stored in the dam is first transformed into kinetic energy and subsequently this kinetic energy of flowing water rotates the turbines of power plant and electrical energy is produced.
(b) During evaporation process at sea level, a part of the solar energy gets converted into potential energy of water molecules, which rise up in the air to form clouds. The potential energy of water molecules in clouds gets converted into kinetic energy during rain and snowfall. Thus, energy flowing in a river is a river is an indirect form of solar energy.

Explain, how does a hydro power plant produce electricity. [CBSE 2010, 2014, 2015]

A hydro power plant converts the potential energy of stored water into electricity. To produce hydro power electricity, a high rise dam is constructed at a suitable place on the river to obstruct the flow of water and thereby collect water in a large sized reservoir. Due to rise of water level, the kinetic energy of flowing water is transformed into potential energy of stored water.
The water from the high level in the dam is carried through sluice gates and pipes to the turbine of electric generator, which is fitted at the bottom of the dam. Due to flowing water, turbine is rotated at a fast rate and electricity is produced.

Mention advantages and disadvantages of producing hydroelectricity by building dams on rivers. [CBSE 2013]

Advantages:
(i) The potential energy of water at the top of the dam is readily available to rotate the turbine blades at the bottom of the dam.
(ii) The available water is used for irrigation purposes.
(iii) Occurrence of floods during rainy seasons can be controlled by constructing dams.
(iv) Since the water in the reservoir should be refilled each time it rains; hydro power is a renewable source of energy.
Disadvantages:
(i) Dams can be constructed at a limited number of places, generally in hilly terrain only.
(ii) Large areas of land get submerged when dams are built on rivers. This causes, many long term environmental and social problems.
(iii) It adversely affects the ecosystem of adjoining as well as downstream regions.

What is a dam? Why do we seek to build large dams? While building large dams, which three main problems should particularly be addressed to maintain peace among local people? Mention them. [CBSE 2018]

A dam is a huge construction being done to obstruct the river flow at the place. As a result, a large artificial lake is created there which can be used to store water.
We want to build large dams so as to store large amount of water, which can then be used to produce electricity by means of a hydropower plant.
While building large dams, following three main problems should particularly be addressed to maintain peace among local people:
(i) Construction of dam involves submerges of large areas of agriculture and forest land and human habitation.
(ii) Large eco systems are destroyed.
(iii) Problems of satisfactory rehabilitation of displaced people is a major problem.

Explain the term ‘tidal energy’. How is electricity produced from tidal energy? [CBSE 2014, 2016]

Tidal energy is the kinetic energy possesses by the rising and falling water in seas and oceans during high and low tides respectively.
To harness tidal energy, a dam is constructed across a narrow opening to the sea. The water moves in and out of the openings in the dam during high and low tides. As the water moves through the openings it flows over the turbines fixed inside the dam the dam that generate electricity.

Question: Mention three ways to reduce the pollution caused by fossil fuels. [CBSE 2013, 2016]
Answer: Three possible ways to reduce the pollution caused by the fossil fuels are:

    • Increase the efficiency of the combustion process.
    • Adequate technique must be employed so as to reduce the escape of harmful gases and ash in the surrounding.
    • The fossil fuel may be used to generate electricity which can then be conventionally used in homes and industry.
10th Science Chapter 14 Board Questions Set – 14 (3 Marks)
(i) Name the four gases commonly present in bio-gas. (ii) List two advantages of using bio-gas over fossil fuels. [CBSE 2010, 2012, 2013, 2016, 2019]

(i) The four gases commonly present in bio-gas are methane, carbon-dioxide, hydrogen and hydrogen Sulphide.
(ii) Main advantage of using bio-gas over fossil fuels are as given below:
1. Bio-gas is an excellent fuel as it contains upto 75% methane which burns without smoke.
2. Bio-gas burns completely and leaves no residue i.e. ash.
3. Bio-gas is a renewable, convenient and efficient source of energy, whose heating capacity is high.
4. It gives us a safe method to dispose off wastes like animal dung, human excreta and other bio-waste.

Suggest two materials that can be used to produce bio-gas. Mention two uses of bio-gas and two advantages of bio-gas plant. [CBSE 2010, 2011]

Animal dung, sewage, crop residue etc., can be used to produce bio-gas.
Uses of bio-gas are:
1. Bio-gas is an excellent fuel as it contains upto 75% methane which burns without smoke.
2. Bio-gas burns completely and leaves no residue i.e. ash.
3. Bio-gas is a renewable, convenient and efficient source of energy, whose heating capacity is high.
4. It gives us a safe method to dispose off wastes like animal dung, human excreta and other bio-waste.
Advantages of a bio-gas plant are:
(i) It provides an efficient and safe method to dispose off waste materials.
(ii) The slurry left in a bio-gas plant can be used as manure because it is rich in nitrogenous and phosphorus compounds.
(iii) A bio-gas plant can be installed anywhere at a small cost.
(iv) It does not cause any pollution or contamination of environment.

(a) How charcoal is better fuel than wood? Why? (b) How does bio-gas plant help to reduce the problem of pollution? [CBSE 2015, 2016]

(a) Charcoal is a better fuel than wood because it burns without flames is comparatively smokeless and has a higher heat generation efficiency.
(b) A bio-gas plants help to reduce the problem of pollution by utilizing waste bio-mass by producing bio-gas and manure.

Describe the step involved in obtaining bio-gas and explain what is meant by anaerobic decomposition. [CBSE 2011, 2013]

The following steps are involved in obtaining bio-gas:
(i) Bio-mass suitable for production of bio-gas is collected. Bio-mass includes animal dung, sewage, crop residue, vegetable wastes etc.
(ii) A slurry of bio-mass with water is made in a mixing tank called digestor for degrading by anaerobic micro-organism. These tanks are sealed chambers.
(iii) In order to get a continue supply of bio-gas the plant is fed regularly with waste. Anaerobic decomposition means breaking down the complex compounds of bio-mass in the slurry in the presence of water by microorganism.

What is the use of bio-mass generate heat: (i) discouraged from burning it directly in ovens and, (ii) encouraged for obtaining bio-gas through a bio-gas plant? {CBSE 2011, 2013]

(i) Use of bio mass to generate heat by burning it directly in open chulahs in discouraged because it not an efficient way to produce heat and lot of smoke and ash is produced.
(ii) Use of bio-masses is encouraged to obtain bio-gas because it utilise water material and helps control pollution. The bio-gas is a very good fuel and good quantity manure is obtained as a by-product.

Question: Write one advantage of nuclear fission reaction. [CBSE 2007, 2015]
Answer: In a nuclear fission reaction large amount of energy is released by a small quantity of nuclear fuel, which can be easily converted into electrical energy.

10th Science Chapter 14 Board Questions Set – 15 (3 Marks)
What is thermal power plant? How does it work? Why do we prefer to set up a thermal power plant near a coal or oil field? [CBSE 2010, 2011, 2014]

Thermal power plant is a large sized assembly in which fossil fuel or CNG is burnt to produce heat energy which is converted into electrical energy. In thermal power plant large amount of fossil fuel is burnt every day to heat up water to produce steam. This stream is utilised to run the turbine to generate electrical energy. We prefer to set up thermal power plant near coal or oil fields. It is because transmission of electricity is more efficient than transporting coal or petroleum over the same distance

How can one say that Sun is the main sources of energy on the earth? [CBSE 2015]

Solar energy manifest itself in many forms through many process both biological and physical. Plants utilise solar energy for photosynthesis. The solar energy trapped by land and water bodies brings about many physical changes resulting in wind, storm, ocean waves, etc. Also fossil fuels example coal, natural gas, petrol etc., have been formed due to very slow changes which occurred millions of years ago and were related to solar energy. Energy of bio-gas etc., is also delivered from solar energy.

What are solar cells? Explain the structure of solar panels, list any two principal advantages associated with the solar cells. [CBSE 2019]

A solar cell is a device which convert solar energy directly into electricity. The box of solar cooker is made of non-conducting material example plastic or fibre glass with thick inner wall. These walls are painted in black. A plane mirror is hinged on the top so that it reflects sunlight into the box.

State any three limitation of harnessing nuclear energy. [CBSE 2016]

Three main limitation of harnessing nuclear energy are as follows:
(i) The most important problem is to storage and disposal of spent or used fuel because it is highly radioactive. Improper nuclear storage and disposal may lead to environmental contamination.
(ii) There is a risk of accidental leakage of nuclear radiation from the nuclear reactor.
(iii) Cost of installation of a nuclear power plant is very high.

Name the major fuel component of bio-gas. What are its other combustible components? What is the use for the residual slurry and Why? [CBSE 2010, 2012]

The major fuel component of bio-gas is methane gas. It consists about 75% of total bio-gas. Other combustible components of bio-gas plant are hydrogen and hydrogen Sulphide gases. Residual slurry from bio-gas plant is used as manure because it is rich in nitrogen and phosphorous.

Question: Mention any four areas where solar cells are being used as a source of energy. [CBSE 2011, 2012]
Answer:

    1. In artificial satellite as source of energy.
    2. As source of electricity for radio broadcast and TV relay stations.
    3. Traffic lights and research centers in remote areas.
    4. In calculator and toys.
10th Science Chapter 14 Board Questions Set – 16 (5 Marks)
Explain Why: (i) It is difficult to burn a piece of wood fresh from a tree. (ii) Pouring dry sand over the fire extinguish it. (iii) It is difficult to use hydrogen as a sources of energy. (iv) Charcoal is considered a better fuel than wood. [CBSE 2016]

(i) It is because a pieces fresh wood is not dry and therefore, it is to be heated at high temperature before it catches fire, that is why it is difficult to burn.
(ii) It cuts off the supply of air which is required for combustion to take place.
(iii) Hydrogen is highly combustible and burns with an explosion, therefore, it is difficult to store and transport.
(iv) Charcoal has higher calorific value than wood and produces less smoke than wood.

Burning of fossil fuels causes lots of air pollution. Generally, these fossil fuels are used in our vehicle. (i) As a citizen list two ways to reduce air pollution. Caused due to vehicles. (ii) Write two harmful effects other than air pollution that are caused due to burning of fossil fuels. [CBSE 2015]

(i) Two ways to reduce air pollution caused due to vehicles are follows:
(a) The petrol used should be free of lead and sulphur impurities because oxides of these elements are toxic and cause much air pollution.
(b) Vehicle using diesel should be replaced by vehicles using CNG as a fuel.
(ii) two harmful effects other than air pollution, caused due to burning of fossil fuels are as follows:
(a) Burning of fossil fuels produce oxides of nitrogen and sulphur. These gases are acidic in nature and lead to acid rain which adversely affects our water and soil resources.
(b) Burning of fossil fuels produce carbon dioxide which is a greenhouse gas and leads to global warming causing a lot environmental and ecological problems.

How is nuclear energy generated? State in brief the process of utilizing this energy in the production of electricity. Mention the major hazard of nuclear power generation. [CBSE 2010, 2011, 2012, 2016]

Nuclear energy is generated by the process of nuclear fission. The nuclear of a heavy atom such as uranium or plutonium. When bombarded with low energy neutrons can be split apart into two lighter nuclei along with the release of tremendous amount of energy. We design a nuclear reactor in which process of nuclear fission take place at a sustained rate and energy is released at a uniform rate. This energy is utilised to convert water into steam which then does work for rotating turbine of electric generator. As a result, electricity is produced.
The major hazards of nuclear power generation are to storage and safe disposal of spent or used fuel so that no environment contamination take place.

What is a bio-mass? Explain the principal and working of a bio-gas plant. [CBSE 2008, 2010, 2011, 2014]

Animal dung, crop residue, vegetable waste and sewage constitute the bio-mass. In a bio gas plant slurry of animal dung or other types of bio-waste and water is made in the mixing tank and then feed into the digester. The digester is usually a closed underground tank. In digester the action of micro-organism decomposes the complex compound of bio-mass in the slurry. In the presence of water anaerobic micro-organism degrade the bio-mass in the digester. As anaerobic microorganism do not require oxygen the digester is designed like a sealed chamber. The complete degradation process take place few days during which bio-gases are produced. Now the bio-gas can be supplied to consumers through pipes. Periodically the slurry that is left behind the digester is removed and it serves to as an excellent manure.

Why is not possible to make use of solar cells to meet all our energy needs? State at least reasons to support your answer. [CBSE 2010, 2011, 2012]

Although solar cell panels a clean pollution free and environment friendly source of electricity yet they can be used for a limited purpose and fail to meet all our domestic needs of electricity due to the following reason.
(i) Their installation cost is very high on account of following: (a) Special grade silicon required for making solar cell is also limited. (b) Technology to obtain silicon in pure form is expensive. (c) Silver conductor is to be used for connecting solar cells in solar panels, which is again very expensive.
(ii) There is a practical problem of availability of efficient system that can store electricity generated by solar cells and make it availability when required. Storage batteries and inverters are to be used. It again enhances the cost and reduce the efficiency.
(iii) Solar panels cannot work on cloddy and rainy days.

Question: What are main advantages of solar energy? [CBSE 2010, 2011, 2012]
Answer: Main advantages of solar energy are as follows:

    • No fuel or electricity is needed for harnessing solar energy.
    • The solar energy is available in abundance and it can be obtained anywhere even in remote areas.
    • The upkeep and maintenance of solar energy device requires normal expenditure only.
    • It is environmental friendly.
    • There is no reduce like ash, which is to be disposed off.

Question: Name two semiconductor used in solar cell. What is solar cell panel? State two main advantages of solar panel. [CBSE 2010, 2012, 2013]
Answer: Silicon and gallium are two semiconductors commonly used in solar cell. A solar panel is an arrangement in which a large number of solar cells are combined so that it can deliver enough electricity for practical use.
Solar panels have followings advantages:

    1. They have no moving parts, require little maintenance and work quite satisfactory without the use of any focusing device.
    2. These can be set up in remote and inaccessible hamlets or very sparsely populated areas where lying of a power transmission line is not commercially viable.