Sources of Energy Class 10 Science Exam Questions

Exam Questions Class 10

Please refer to Sources of Energy Class 10 Science Exam Questions provided below. These questions and answers for Class 10 Science have been designed based on the past trend of questions and important topics in your class 10 Science books. You should go through all Class 10 Science Important Questions provided by our teachers which will help you to get more marks in upcoming exams.

Class 10 Science Exam Questions Sources of Energy

Class 10 Science students should read and understand the important questions and answers provided below for Sources of Energy which will help them to understand all important and difficult topics.

Very Short Answers Type Questions

Question. Name two forms of energy in which solar energy manifests itself in oceans.
Answer : (a) Tidal energy and (b) Ocean thermal energy.

Question. What is a chain reaction ?
Answer : A reaction in which the particle which initiates (starts) the reaction is also produced during the reaction to carry on the reaction further and further is called a chain reaction.

Question. Which part of Sun’s energy is responsible for drying clothes and exposure to which part could be a health hazard ?
Answer : Infra-red (IR) radiations are responsible for drying clothes and ultraviolet (UV) radiations could be a health hazard.

Question. Bio-gas is also known as gobar gas. Justify.
Answer : Starting material for biogas is mainly cow-dung. So, it is also known as gobar gas.

Question. Why does acid rain happen ?
Answer : Acid rain happens because of burning of fossil fuels which release oxides of carbon, nitrogen and sulphur in the atmosphere.

Question. Though a hot iron emits radiations, yet it is not visible in the dark, why ?
Answer : Hot iron emits infra-red rays. These rays are invisible to the eyes.

Question. What is the use of the black painted surface in solar heating devices ?
Answer : Black colour is a very good absorber of heat but a very poor reflector. So, it is used to absorb the maximum amount of heat from the sunlight. It is used in solar heating devices to maximise the absorption of heat and to minimize heat loss due to reflection.

Question. Name two constituents of biogas.
Answer : Two constituents of biogas are methane (CH4) and Hydrogen

Question. What is the importance of the digester of a biogas plant ?
Answer : The digester of a biogas plant is a sealed chamber in which anaerobic micro-organisms that do not require oxygen decompose or break down complex compounds of the cow-dung slurry.

Question. What do you mean by the term ‘thermal power plant’ ?
Answer : Thermal power plant is the power plant where coal is burnt to produce heat energy which is converted into electrical energy.

Question. ‘‘Burning fossil fuels is a cause of global warming.’’ Give reason in support of this statement.
Answer : Burning of fossil fuel produces CO2, oxides of sulphur and nitrogen. CO2 is a greenhouse gas, its excess produces greenhouse effect, increasing earth’s temperature and causes global warming.

Question. If you could use any source of energy for heating your food which one would you prefer? State one reason for your choice.
Answer : I would prefer a solar cooker for heating food because solar cooker is environmental friendly and causes no pollution.

Question. Why geothermal energy is called a renewable source of energy ?
Answer : Geothermal energy is a renewable source of energy because it will be available for a long time and heat is continuously produced inside the earth.

Short Answers Type Questions

Question. What are solar cells ? Explain the structure of solar panel. List two principal advantages associated with solar cells.
Answer : Solar cells are the devices which convert solar energy into electricity.
A simple solar cell is made up of sandwich of a siliconboron layer and a silicon-arsenic layer. Boron and arsenic are present in a very small amount. A piece of wire is soldered into the top of upper layer of cell and another piece of wire is soldered at the bottom of the lower layer to pass on the current. The solar cell is covered with a glass cover for protection.
Advantages :
(a) Solar cells have no moving parts.
(b) It requires less maintenance.

Question. While discussing about coal and petroleum a teacher told his students about PCRA’s (Petroleum Conservation Research Association) guidelines to save the fossil fuels while driving vehicles. Deepa was going to her school with her mother who was driving car. At the traffic signal, when the light was red, Deepa suggested her mother to switch off the engine. After reading the above passage, answer the following questions :
(a) Fossil fuels are natural resources, then why do we need to conserve them ?
(b) List any two ways of saving the fossil fuels.
Answer : (a) Fossil fuels take millions of years in their formation, hence are exhaustible and need to be conserved to provide energy for a longer duration and sustainable development.
(b) Walking short distances or use of public transport. Where possible switch off unnecessary lights.

Question. Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer : Fossil fuels are non-renewable energy sources and directly available to human beings for use. Hence, fossil fuels are the direct source of energy. These are limited in amount. Fossil fuels take millions of years for their formation. Fossil fuels are also very costly. On the other hand, sun is a renewable and direct source of energy. Solar energy is available free of cost to all in unlimited amount for billions of years.

Question. Give the names of two energy sources that you consider to be exhaustible. Give reason for your choices.
Answer : Two exhaustible energy sources are as follows :
Coal : It is produced from dead remains of plants and animals that remain buried under the earth’s crust for millions of years. It takes millions of years to produce coal. Industrialisation has increased the demand of coal. However, coal cannot replenish within a short period of time. Hence, it is a non-renewable or exhaustible source of energy.
Wood : It is obtained from forests. Deforestation at a faster rate has caused a reduction in the number of forests on the earth. It takes hundreds of years to grow a forest. If deforestation is continued at this rate, then there would be no wood left on the earth. Hence, wood is an exhaustible source of energy.

Question. Compare and contrast biomass and hydroelectricity as sources of energy.
Answer : (a) Hydroelectricity is generated using the kinetic energy from moving water, while the energy from biomass is generated by decomposition of farm waste.
(b) Biomass is composed of organic compounds so, energy from biomass results in air pollution whereas hydroelectricity causes less pollution as compared to it.

Question. List three environmental consequences of using fossil fuels. Suggest three steps to minimise the pollution caused by various energy sources.
Answer : The combustion of fossil fuels releases different harmful products. Three environmental consequences of using fossil fuels are :
(a) It releases CO2 which is a greenhouse gas which traps the solar energy falling on earth and it leads to global warming.
(b) Carbon monoxide is poisonous gas which when enters in the blood stream stops the functioning of red blood cells to carrying oxygen from lungs to other parts of the body. It also causes death.
(c) Sulphur dioxide released during the burning of fossil fuels is harmful for lungs and causes bronchitis and other diseases.
Steps to minimise the pollution caused by various energy sources are :
(a) Solar cookers should be used to cook food wherever possible.
(b) Use of biogas as domestic fuel should be encouraged in rural areas.
(c) Three R’s strategy–Reduce, Reuse and Recycle should be practiced.

Question. Give reason : “A car parked in sunlight remains hot from inside even when there is no sunlight in the car”.
Answer : The glass windows have the ability to pass the radiations which have wavelength near to the visible light or shorter wavelength. It does not allow infra-red radiations of higher wavelength. However, the sun sends infrared radiations of lower wavelength which pass through the glass windows and gets trapped inside the car as heat. This heat does not pass out of the car and remains inside the car for longer time.

Question: What is the main constituent of biogas? How is biogas obtained from biomass? Write any two advantages of using this gas. 
Answer: The main constituent of biogas is methane (75%). Biogas is obtained by anaerobic decomposition of biomass in biogas plant. The two advantages of using this gas are
(i) It does not produce smoke.
(ii) It has high calorific value.

Question: (a) Write Einstein’s mass-energy equation. Give the meaning of each symbol which occurs in it.
(b) In nuclear fission of a piece of uranium, 0.5 g of mass is lost, how much energy in MeV is obtained ?
Answer : (a) According to Einstein, mass and energy are interchangeable and are related by the equation :
E = (Δm) c2
Here, Δm is the loss in mass in kg, c is the speed of light (3 × 108 ms–1) and E is the energy in joule (J).
(b) Here, Δm = 0.5 g = 0.5 × 10–3 kg, c = 3 × 108 ms–1 and
1 MeV = 1.6 × 10–13 J
∴ Energy released, E = (Δm) c2

Question: What are fossil fuels? “Burning fossil fuels may lead to intense global warming.” Justify this statement. 
Answer: Fossil fuels : The combustible substances formed from the dead remains of the animals and plants which were buried deep under the surface of the earth for over millions of years are called fossil fuels. Burning of fossil fuels produces carbon dioxide and excess carbon dioxide in the atmosphere causes the greenhouse effect, leading to intense global warming.

Question: Mention any four limitations in harnessing wind energy on a large scale.
Answer: Limitations in harnessing wind energy on a large scale are :
(i) Wind energy farms can be established only where the minimum velocity of wind is 15 km/h.
 (ii) The kinetic energy of wind can be used only at the site of a windmill.
(iii) Wind energy cannot be used to operate all types of machines.
(iv) It is expensive to set up a wind farm for generating electricity because wind farms need a large area. 

Question: Define :
(i) Biomass
(ii) Anaerobic degradation 
Answer: (i) Biomass : Cow-dung, various plant materials like the residue after harvesting the crops, vegetable wastes and sewage which can be decomposed in the absence of oxygen is called biomass.
(ii) Anaerobic degradation : Breaking of large organic molecules into simple molecules in the absence of air is called anaerobic degradation.

Question: List any four disadvantages of using fossil fuels for the production of energy. 
Answer: Disadvantages of using fossil fuels for the production of energy are :
(i) Fossil fuels are non-renewable source of energy.
(ii) It causes air pollution to the environment.
(iii) It takes millions of years for its formation.
(iv) It causes acid rain.

Long Answers Type Questions

Question. What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumptions ?
Answer : Environmental consequences of increasing demand for energy are as follows :
(a) Use of fossil fuels is increasing air pollution which is not good for our health.
(b) Air pollution is causing much damage to the ecosystem.
(c) Greenhouse effect has resulted in global warming which is manifesting itself in strange changes in the weather pattern around the world.
(d) Too much exploitation of fossil fuels is going to create a situation when there would be no fossil fuel.
Steps to reduce energy consumption :
(a) Use your household appliances efficiently.
(b) Use public transport instead of private modes of transport.
(c) Use bicycle whenever possible.
(d) Walk for short distance to commute.
(e) Avoid unnecessary use of modern gadgets which consume lot of energy.
(f) Get a solar water heater installed for winters.

Question. What are the merits and limitations of the energy that can be obtained from the deep inside the earth ?
Answer : Merits of geothermal energy :
(a) It is a renewable source of energy.
(b) It involves low running cost.
(c) It does not create any pollution and help in creating clean environment.
(d) Maintenance cost of geothermal power plant is low.
(e) Geothermal power plants are unaffected by weather and night cycle day.
Limitations of geothermal energy :
(a) Geographically, there are very limited number of places where geothermal power plants are likely to operate effectively.
(b) Enhanced geothermal system can trigger earthquakes, therefore it affect land stability severly.
(c) High up front installation cost required for construction of geothermal power plant and its drilling wells, which requires advance technology.
(d) There is an abundance of greenhouse gases below the earth surface. They can might be escape through the holes drilled during constructions. It leads to global worming and acid rain.
(e) Geothermal Energy cannot be easily transported unlike other source of energy.

Question. (a) What is a biogas plant ?
(b) Name five main parts of fixed dome type biogas plant.
(c) Draw a neat labelled diagram of a fixed dome type biogas plant.
Answer : (a) The arrangement used for producing biogas from animal dung, human excreta, and domestic waste is known as biogas plant.
(b) A fixed dome type biogas plants consist of :
(i) Mixing tank : In this, slurry, animal dung and other waste materials are mixed.
(ii) Digester : It is a well like underground tank made up of bricks and cement. It has outlet and inlet valves. The roof of the digester is dome shaped. The dome acts as a storage tank of biogas. A gas outlet is fitted at the top of the dome.
(iii) Inlet chamber : It is situated on one side of the digester. It passes the slurry of cattle dung and other waste from the mixing tank to the digester.
(iv) Outlet chamber : It is on the other side of the digester. It is rectangular in shape and constructed with bricks and cement. It is connected to the overflow tank.
(v) Overflow tank : It collects the used slurry or spent slurry. This spent slurry can be used as manure.

Sources of Energy Class 10 Science Exam Questions

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