GSEB Class 10 Science Solutions Chapter 14 Sources of Energy

Gujarat Board Class 10 Science Sources of Energy InText Questions and Answers

 

Question 1. What is a good source of energy?
Answer: A good energy source is one that is readily available, inexpensive, and does not cause environmental harm. These characteristics make it a desirable choice.
In simple words: A good energy source is easy to find, affordable, and doesn't pollute.

Exam Tip: When defining a "good" source, always mention its availability, cost-effectiveness, and environmental impact.

 

Question 2. What is a good fuel?
Answer: A good fuel is inexpensive, easy to obtain, simple to handle and move, has the correct ignition temperature, and a high heat value. These qualities make it effective for various uses.
In simple words: A good fuel is cheap, easy to get, simple to use, lights up at the right temperature, and produces a lot of heat.

Exam Tip: Remember to include characteristics like availability, handling, ignition temperature, and calorific value when describing a good fuel.

 

Question 3. If you could use any source of energy for heating your food, which one would you use, and why?
Answer: If the sun's heat is reachable, a solar cooker would be an excellent choice. Otherwise, compressed natural gas (CNG) is a suitable alternative for heating food. Both options offer practical benefits.
In simple words: I would use a solar cooker if there's sun, or CNG if not, to heat my food.

Exam Tip: Consider renewable sources first for heating food, noting their conditions of use, and then suggest efficient, readily available non-renewable options.

 

Question 4. What are the disadvantages of fossil fuels?
Answer: Disadvantages of fossil fuels include:
(a) They are resources that cannot be renewed, meaning their supply is limited.
(b) They create pollution, which can lead to:

• Acid rain
• Smoke
• Greenhouse effect due to \( \text{CO}_2 \)
• Fine ash particles suspended in the air.

These issues highlight the environmental impact of their use.
In simple words: Fossil fuels run out, and they cause pollution like acid rain, smoke, and greenhouse gases.

Exam Tip: List both the finite nature of fossil fuels and the various forms of environmental pollution they generate.

 

Question 5. Why are we looking at alternate sources of energy?
Answer: The energy sources we currently use, such as fossil fuels like petrol, petroleum products, and coal, are finite and cannot be renewed. Energy demand is growing because of increasing populations and improved technology that has added many machines and appliances for a better lifestyle. So, energy demand rises every day. To solve this issue, we are seeking alternative energy sources.
In simple words: We need new energy sources because current ones are running out, and our energy needs are growing due to more people and technology.

Exam Tip: Focus on the two main reasons: depletion of existing sources and increasing global energy demand due to population growth and technological advancement.

 

Question 6. How has the traditional use of wind and water energy been modified for our convenience?
Answer:

• The conventional use of water energy has changed; we now build dams, install turbines, and use dynamos to generate electricity from flowing water.
• Wind energy is now harnessed to turn windmills and turbines, which then generate electricity by using specially built wind fans.

These modifications make these sources more useful for modern needs.
In simple words: We've changed how we use water and wind energy by building dams for electricity and using windmills with turbines to make power.

Exam Tip: Explain how modern technology (dams, turbines, dynamos, windmills) has enhanced the older methods of harnessing wind and water power.

 

Question 7. Which type of mirror – convex or plain – would be best suited for use in a solar cooker? Why?
Answer: A concave mirror would be most suitable for a solar cooker. This is because it acts as a converging mirror, meaning it gathers the sun's heat radiation and directs it to a single focused spot, making heating more effective.
In simple words: A concave mirror works best in a solar cooker because it collects sunlight and focuses it to one hot point.

Exam Tip: Remember that concave mirrors are converging mirrors, which is key to their effectiveness in solar cookers for concentrating sunlight.

 

Question 8. What are the limitations of the energy that can be obtained from the oceans?
Answer: The limitations of obtaining energy from the ocean are:

• Only a few specific locations exist where wave, tidal, or ocean thermal energy can be successfully gathered.
• Building the necessary power plants is very costly.
• The process of generating this energy often has low efficiency.

These factors limit its widespread use.
In simple words: Ocean energy is limited because there are few good spots to get it, building plants costs a lot, and it's not very efficient.

Exam Tip: Focus on the three main limitations: geographical constraints, high infrastructure costs, and low energy conversion efficiency.

 

Question 9. What is geothermal energy?
Answer: Geothermal energy refers to the heat energy that we get in the form of steam from beneath the Earth's surface. This natural heat source is used for various purposes.
In simple words: Geothermal energy is heat from inside the Earth, usually as steam.

Exam Tip: Define geothermal energy by mentioning its origin (Earth's crust) and form (heat/steam).

 

Question 10. What are the advantages of nuclear energy? (CBSE 2011)
Answer: The advantages of nuclear energy are:

• A very small quantity of radioactive material can create a huge amount of energy, which can be managed and turned into a usable form. For instance, 1 kg of Uranium produces as much energy as 25 thousand tonnes of coal.
• It does not release any smoke or harmful gases into the air, which helps to reduce global warming caused by the greenhouse effect.

These benefits highlight its power and environmental impact.
In simple words: Nuclear energy uses little material to make lots of power and doesn't pollute the air, helping with global warming.

Exam Tip: Emphasize the high energy yield from small amounts of fuel and its minimal air pollution impact.

 

Question 11. Can any source of energy be pollution-free? Why or why not?
Answer: Yes, some sources of energy can be pollution-free when used. For example, solar energy, which is utilized in a solar cooker, solar water heater, or solar cell panels, does not create pollution during its operation. These methods offer clean energy solutions.
In simple words: Yes, solar energy is pollution-free when used in things like solar cookers or panels.

Exam Tip: Provide a clear 'yes' or 'no' answer, then support it with specific examples of pollution-free energy sources like solar power.

 

Question 12. Hydrogen has been used as rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer: Hydrogen is indeed a cleaner fuel than CNG. When hydrogen burns or undergoes combustion, it creates water. In contrast, CNG, which contains methane, burns to produce carbon dioxide, a greenhouse gas. This difference in byproducts makes hydrogen more environmentally friendly.
In simple words: Hydrogen is cleaner than CNG because it produces water when burned, while CNG makes carbon dioxide.

Exam Tip: Compare the combustion products: hydrogen produces water (clean), while CNG produces carbon dioxide (polluting).

 

Question 13. Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer:

• Solar energy – This source will not run out. It can be used for many purposes, such as heating, burning, and generating electricity. It causes no pollution, is inexpensive, and is readily available.
• Energy from water – Power can be obtained from water in various forms, for instance, for generating electricity without causing pollution.

These options provide sustainable energy.
In simple words: Solar energy won't run out, is clean, and cheap. Water energy can make electricity without pollution.

Exam Tip: For renewable sources, clearly state why they are renewable (don't deplete) and mention key advantages like being pollution-free and versatile.

 

Question 14. Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer: Petroleum and coal are considered exhaustible energy sources. This is because once they are fully consumed, they cannot be replaced within a short timeframe. They take millions of years to form again, making their supply finite.
In simple words: Petroleum and coal are exhaustible because they cannot be renewed once used up.

Exam Tip: Define exhaustible sources by explaining that they are finite and cannot be renewed once used.

In-Text Activities Solved

Activity 14.1

 

Question. List four forms of energy that you use from the morning when you wake up until you reach the school. From where do we get these different forms of energy? Can we call these 'source' of energy? Why or why not?
Answer: The four forms of energy used from morning until school are:

• Electrical energy – for ironing clothes and lighting.
• Muscular energy – for brushing teeth and taking a bath.
• Heat energy – for cooking food and room heaters.
• Chemical (food) energy – from breakfast, aiding respiration and digestion.

The sources for these different forms of energy are:

• Electrical energy – from power plants.
• Muscular energy – energy stored in our body from the food we consume.
• Heat – from various fuels.
• Chemical energy – from breakfast.

Yes, all of these can be called 'sources' of energy because they provide the power needed to perform different tasks and processes.
In simple words: We use electricity for irons, muscle power for brushing, heat for cooking, and food for body energy. These all come from sources like power plants, our food, and fuels. Yes, they are all energy sources.

Exam Tip: When listing energy forms, ensure to also state their corresponding sources and clarify why they are considered sources. Provide diverse examples for each category.

Activity 14.2

 

Question. Consider the various options we have when we choose fuel for cooking our food. What are the criteria you would consider when trying to categorize something as a good fuel? Would your choice be different if you lived (a) in a forest? (b) in a remote mountain village or small island? (c) in New Delhi? (d) lived five centuries ago? How are the factors different in each case?
Answer:
1. To choose fuel for cooking food, the following criteria are important:
(a) It should have a higher calorific value (produce more heat).
(b) It should have a suitable ignition temperature.
(c) It should not produce any smoke or ash.
(d) It should be easily available, simple to handle, and transport.
2. Our fuel choice would differ based on the following conditions:
(a) If one lived in a forest, wood would likely be the primary fuel.
(b) In a secluded mountain village or small island, dry leaves, small twigs, wood, and cow dung cakes would be common fuels.
(c) In New Delhi, LPG (Liquefied Petroleum Gas) or CNG (Compressed Natural Gas) would be the preferred options.
(d) If one lived five centuries ago, wood would be the dominant fuel source.
4. Availability is the main consideration when selecting a fuel source in each scenario.
In simple words: When choosing cooking fuel, we look for high heat, easy lighting, no smoke, and easy access. Where you live changes your fuel choice: wood in a forest, leaves or dung in a village, LPG/CNG in a city, and wood in the past. Availability is key.

Exam Tip: Clearly list the general criteria for good fuel, then provide specific examples for each hypothetical scenario, highlighting availability as the driving factor.

Activity 14.3

 

Question. Take a table tennis ball and make three slits into it. Put semicircular fins cut out of a metal sheet into these slits. Pivot the tennis ball on an axle through its center with a straight metal wire fixed to a rigid support. Ensure that the tennis ball rotates freely about the axle. Now connect a cycle dynamo to this. Connect a bulb in series. Direct a jet of water or steam produced in a pressure cooker at the fins. Describe the observation and explain the model.
Answer:
Observation: The bulb lights up.
Explanation: This setup demonstrates thermoelectric production. A turbine consists of a moving rotor-blade assembly. The moving fluid (water or steam jet) hits the blades, causing them to spin and transfer energy to the rotor. When the rotor spins, it turns the shaft of the dynamo, converting the mechanical energy into electrical energy, which then lights the bulb. This model illustrates how kinetic energy from a fluid can be transformed into electrical energy.
In simple words: When steam or water hits the fins on the spinning ball, it turns a dynamo, which creates electricity and lights a bulb. This shows how movement can make power.

Exam Tip: For experiment descriptions, clearly state the observation and then provide a concise explanation linking the setup to the scientific principle (e.g., energy conversion).

Activity 14.4

 

Question. Find out from your grandparents or other elders - (a) how did they go to school? (b) how did they get water for their daily needs when they were young? (c) what means of entertainment did they use? Compare the above answers with how you do these tasks now. Is there a difference? If yes, in which case more energy from external sources is consumed?
Answer:
From our grandparents/elders:
(a) Our grandparents typically walked, used bicycles, or traveled by tonga (horse-drawn carriage) to go to school.
(b) They fetched water for their daily needs from wells, borewells, or rivers.
(c) Fairs, group games, and dancing were common forms of entertainment for them.
Comparison with today:
Today, we:
(a) go to school in a school bus or car.
(b) get water using submersible pumps.
(c) are often focused on TV, mobile phones, and computers for entertainment.
Yes, there is a significant difference. Today, more energy from external sources is consumed for transportation, water supply (electricity for pumps), and electronic entertainment devices.
In simple words: Grandparents walked or rode bikes to school, got water from wells, and played games for fun. Today, we use cars and buses, electric pumps for water, and screens for entertainment. Yes, we now use much more outside energy for these tasks.

Exam Tip: Clearly delineate between past and present practices for each task, then explicitly state whether there's a difference in energy consumption and provide examples.

Activity 14.5

 

Question. Take two conical flasks and paint one white and the other black. Fill both with water. Place the conical flask in direct sunlight for half an hour to one hour. Touch the conical flasks, measure the temperature of the water in the two conical flasks with a thermometer. Can you think of ways in which this finding would be used in your daily life?
Answer:
Observation: The conical flask painted black will contain water at a higher temperature. This shows that dark colors absorb more heat than light colors.
Daily life application: In everyday life, we use this principle by wearing light-colored clothes in summers, which reflect sunlight and help us stay cool. Conversely, we wear dark-colored clothes in winters, which absorb heat and help us stay warm. This property is also used in solar devices to maximize heat absorption.
In simple words: The black flask gets hotter. This means dark colors absorb more heat. We use this by wearing light clothes in summer to stay cool and dark clothes in winter to stay warm.

Exam Tip: For an experiment, always state the clear observation first, and then explain its real-world applications or implications.

Activity 14.6

 

Question. Study the structure and working of a solar cooker and/or a solar water heater, particularly with regard to how it is insulated and maximum heat absorption is ensured. Design and build a solar cooker or water heater using low-cost material available and check what temperatures are achieved in your system. Discuss what would be the advantage and limitations of using the solar cooker or water heater.
Answer:
Construction and Working of a Solar Cooker:

• A black box is used to absorb heat.
• A glass sheet creates a greenhouse effect, trapping heat inside.
• A mirror is used to reflect the sun's heat into the box, focusing it.

Advantages of a Solar Cooker:
(a) It is inexpensive and easy to handle.
(b) It does not require any fuel for cooking.
(c) It is pollution-free.
Disadvantages of a Solar Cooker:
(a) Cooking is quite slow and takes a long time.
(b) It relies on sunlight and cannot operate on cloudy days.
(c) The position of the reflectors must be adjusted to ensure sunlight is focused at the cooker's center. For areas with insufficient sunlight, solar cooker use would be limited.

In simple words: Solar cookers have a black box, glass, and mirror. They are cheap, use no fuel, and don't pollute. But they cook slowly, only work on sunny days, and need constant mirror adjustment.

Exam Tip: For a comprehensive answer, break down the explanation into construction, advantages, and disadvantages, using clear, concise points for each. Include the functional role of each part (e.g., black box for absorption).

Activity 14.7

 

Question. Discuss in class the question of what is the ultimate source of energy for biomass, wind, and ocean thermal energy. Is geothermal energy and nuclear energy different in this respect? Why? Where would you place hydroelectricity and wave energy?
Answer: The ultimate energy source for biomass, wind, and ocean thermal energy is solar energy, which comes from the Sun. The Sun is the only primary energy source for Earth that drives these processes.

• Geothermal energy is obtained from inside the Earth due to its internal heat and pressure. Nuclear energy is derived from the nuclear reactions of radioactive substances. These two are different from solar energy because their origin is not directly from the Sun.
• Hydroelectricity and wave energy can be categorized under the Sun's energy because both are ultimately formed due to the Sun's heat energy. The Sun drives the water cycle (for hydroelectricity) and creates winds that generate waves.

In simple words: The sun is the main source for biomass, wind, and ocean thermal energy. Geothermal and nuclear energy are different as they come from inside Earth or nuclear reactions. Hydroelectricity and wave energy are linked to the sun because the sun powers the water cycle and winds.

Exam Tip: Identify the ultimate source for each type of energy and clearly explain the underlying processes. Differentiate between solar-derived and non-solar-derived sources.

Activity 14.8

 

Question. Gather information about various energy sources and how each one affects the environment. Debate the merits and demerits of each source and select the best source of energy on this basis.
Answer: Here is a summary of various energy sources and their environmental effects:

The best source of energy on this basis would be solar energy, tidal/wave energy, and geothermal energy due to their minimal environmental effects. However, considering scalability and general applicability, solar energy stands out for its widespread potential and low environmental impact during operation.
In simple words: This table shows how different energy sources affect the environment. Solar, tidal/wave, and geothermal energy are best as they cause little pollution. Solar energy is especially good because it has wide potential and is clean.

Exam Tip: When presenting pros and cons, especially for various sources, use a table for clarity. Conclude by identifying the "best" source based on the discussed criteria, usually environmental impact.

Activity 14.9

 

Question. Debate the following two issues in class. (a) The estimated coal reserves are said to be enough to last us for another two hundred years. Do you think we need to worry about coal getting depleted in this case? Why or why not? (b) It is estimated that the Sun will last for another five billion years. Do we have to worry about solar energy getting exhausted? Why or why not? On the basis of the debate, decide which energy sources can be considered (i) exhaustible, (ii) inexhaustible, (iii) renewable, and (iv) non-renewable. Give your reasons for each choice.
Answer:
(a) We should still be concerned about coal depletion, even if reserves are projected to last for 200 years. This is because huge amounts of coal are burned daily in power stations to heat water and produce steam for electricity generation. Relying solely on coal for such large-scale energy production is unsustainable in the long term, and its environmental impact is substantial.
(b) We do not need to worry about solar energy being exhausted if the Sun lasts for another five billion years. By then, very advanced technology will likely be developed to capture and store solar energy efficiently. Moreover, we will probably have other energy options available for this purpose.
On the basis of this discussion, energy sources can be categorized as:

• Exhaustible – Examples include petrol and coal. These are energy sources that will eventually run out.
• Inexhaustible – Examples include the Sun and water. These are energy sources that are not depleted with use.
• Renewable – Examples include the Sun and water. These are energy sources that are naturally replaced or renewed.
• Non-renewable – Examples include petrol and coal. These are energy sources that, once used, cannot be replaced.

In simple words: We should still worry about coal, even with 200 years' supply, because we burn so much daily, and it pollutes. We don't need to worry about the sun running out because technology will advance, and we'll have other options. Exhaustible fuels like coal run out, while inexhaustible/renewable sources like sun and water don't.

Exam Tip: For debates, address both sides of the argument with reasons. Clearly define and give examples for each energy classification (exhaustible, inexhaustible, renewable, non-renewable).

Gujarat Board Class 10 Science Sources of Energy Textbook Questions and Answers

 

Question 1. A solar water heater cannot be used to get hot water on
(a) a sunny day.
(b) a cloudy day.
(c) a hot day.
(d) a windy day.
Answer: (b) a cloudy day.
In simple words: Solar heaters need sun to work, so they can't heat water on a cloudy day.

Exam Tip: Understand the basic working principle of solar devices – they rely on direct sunlight to function effectively.

 

Question 2. Which of the following is not an example of a bio-mass energy source?
(a) wood
(b) gobar-gas
(c) nuclear energy
(d) coal
Answer: (c) nuclear energy
In simple words: Nuclear energy is not made from living things, so it's not a biomass source.

Exam Tip: Remember that biomass refers to organic matter derived from plants or animals, so identify options not fitting this description.

 

Question 3. Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun's energy?
(a) geothermal energy
(b) wind energy
(c) nuclear energy
(d) bio-mass
Answer: (c) nuclear energy
In simple words: Most energy comes from the sun, but nuclear energy comes from inside atoms, not the sun.

Exam Tip: Understand the ultimate origin of various energy sources. Nuclear energy, geothermal energy, and tidal energy are typically not directly solar-derived.

 

Question 4. Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer:
Sun:

• It is a renewable energy source, meaning it will not run out.
• It does not cause pollution during use.
• It is inexpensive and readily available for most of the time in many places.

Fossil fuels:

• They are non-renewable energy sources and will eventually be exhausted.
• Their use causes significant pollution in the environment.
• They are costly and not always accessible at all times and locations.

This shows key differences in their sustainability and environmental impact.
In simple words: The sun is renewable, clean, and cheap. Fossil fuels are non-renewable, pollute, and are expensive.

Exam Tip: For comparisons, create distinct lists of characteristics for each item, focusing on key attributes like renewability, pollution, and cost/availability.

 

Question 5. Compare and contrast bio-mass and hydroelectricity as sources of energy.
Answer:
Biomass as an Energy Source:

• It causes pollution when burned.
• It is inexpensive and readily available in many regions.
• The initial investment for building a bio-gas plant is very low, and its maintenance costs are also minimal.

Hydroelectricity as an Energy Source:

• It does not cause pollution during operation.
• The initial investment for building a power plant is expensive, and its ongoing maintenance is also costly.

These points highlight their differing economic and environmental profiles.
In simple words: Biomass causes pollution but is cheap to set up. Hydroelectricity is clean but very expensive to build and maintain.

Exam Tip: When comparing energy sources, focus on environmental impact (pollution), initial setup costs, and ongoing maintenance expenses.

 

Question 6. What are the limitations of extracting energy from: (a) the wind? (b) waves? (c) tides?
Answer:
(a) The limitations of extracting energy from wind are:

• It can only be gathered at specific locations where strong winds blow for most of the year.
• The wind must have a minimum speed of 15 km/h for effective generation.
• A large land area is needed to construct a wind farm or windmills, which is a costly undertaking.
• Its efficiency is low, and maintenance expenses are high.

(b) The limitations of extracting energy from waves are:

• The suitable locations and times are restricted to periods when waves are powerful.
• The initial setup cost for wave energy systems is expensive.
• Its efficiency in producing energy is typically low.

(c) The limitations of extracting energy from tides are:

• Few areas exist where tidal energy can be effectively harnessed.
• Its efficiency in converting tidal movement to energy is very low.
• The power plants required are not cost-effective to build and operate.

These factors restrict the widespread use of these ocean-based energies.
In simple words: Wind energy needs specific windy spots, high speeds, lots of land, and is costly to run. Wave energy needs strong waves, is expensive to start, and isn't very efficient. Tidal energy has few good spots, is inefficient, and is expensive to build.

Exam Tip: For each energy source, clearly state physical requirements (e.g., wind speed), geographical constraints (limited sites), and economic factors (cost, efficiency).

 

Question 7. On what basis would you classify energy sources as (a) renewable and non-renewable? (b) exhaustible and inexhaustible? (CBSE 2013)
Answer: Both (a) and (b) options essentially refer to the same classifications based on whether the energy source can be naturally replenished.
Renewable/Inexhaustible:

• These are energy sources that will not run out and can be naturally replenished or created again and again. Examples include solar, wind, and water energy.

Non-renewable/Exhaustible:

• These are also known as exhaustible sources.
• These are energy sources that will deplete and become exhausted, taking millions of years to form. Examples include fossil fuels like petrol and coal.

The classification depends on their ability to regenerate.
In simple words: Renewable or inexhaustible energy sources like sun and water don't run out. Non-renewable or exhaustible sources like petrol and coal will eventually be used up and take a very long time to form again.

Exam Tip: Clearly define renewable/inexhaustible sources as those that replenish naturally and non-renewable/exhaustible as those that are finite and take a long time to form. Provide examples for each.

 

Question 8. What are the qualities of an ideal source of energy?
Answer: An ideal energy source should possess the following qualities:

• It should be inexpensive, readily available, and simple to handle.
• It can be easily transported from one place to another.
• It should have a high calorific value, meaning it produces a lot of heat.
• It should have a suitable ignition temperature for easy combustion.
• It should not cause any environmental pollution.

These attributes ensure efficiency and sustainability.
In simple words: A perfect energy source is cheap, easy to get and move, burns hot, lights easily, and doesn't pollute.

Exam Tip: List key characteristics: cost, availability, handling, transportability, energy content (calorific value), ignition temperature, and environmental impact.

 

Question 9. What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Answer:
Advantages of a solar cooker:
(a) It is inexpensive and simple to manage.
(b) It does not need any fuel for cooking.
(c) It is pollution-free, making it environmentally friendly.
Disadvantages of a solar cooker:
(a) Cooking is very slow and takes a considerable amount of time.
(b) It depends on the sun's light and cannot operate on cloudy days or at night.
(c) The reflectors' position needs to be regularly adjusted to ensure sunlight is focused at the cooker's center point. Yes, in places where sunlight is often insufficient, the use of solar cookers would be limited, such as in regions with frequent cloudy weather or high latitudes during winter.

In simple words: Solar cookers are cheap, don't use fuel, and don't pollute. But they cook slowly, only work on sunny days, and need mirror adjustments. They're not useful where there isn't much sun.

Exam Tip: Structure your answer by clearly separating advantages and disadvantages. For limited utility, explain the specific conditions (e.g., cloudy days, geographic location).

 

Question 10. What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Answer: The environmental consequences of rising energy demand are significant:

• Because of the growing need for energy, our available energy sources are diminishing rapidly.
• Using fuels on a large scale releases many gases and unwanted particles into the air. Gases like \( \text{SO}_2 \) and \( \text{NO}_2 \) cause acid rain, which harms historical buildings, iron objects, bridges, and other structures. This also contributes to the greenhouse effect, leading to global warming, which can melt ice and raise sea levels, submerging coastal areas and islands.

To reduce energy consumption, we should:

• Explore alternative energy sources that can help us overcome these issues.
• Adopt energy-efficient practices in daily life, such as using public transport, turning off lights, and using energy-saving appliances.

In simple words: More energy use means sources run out and pollution increases, causing acid rain and global warming. To fix this, we need to find new energy sources and use less energy.

Exam Tip: When discussing environmental consequences, cover both resource depletion and various forms of pollution (acid rain, greenhouse effect). Suggest practical steps for reduction and the importance of alternative sources.

Gujarat Board Class 10 Science Sources of Energy Additional Important Questions And Answers

Very Short Answer Type Questions

 

Question 1. What is energy?
Answer: Energy is the ability to perform tasks.
In simple words: Energy means you can do work or make things happen.

Exam Tip: Remember that energy is defined by an object's capacity to do work, not just its existence.

 

Question 2. What is a source of energy?
Answer: A source of energy is something that can provide a sufficient amount of practical energy.
In simple words: An energy source gives us enough usable energy.

Exam Tip: Emphasize that a source must provide a *useful* and *adequate* amount of energy for it to be considered effective.

 

Question 3. What is a good source of energy?
Answer: A good energy source needs to be easy to use. It should be able to supply the required amount of energy at a consistent pace for an extended duration.
In simple words: A good energy source is simple to use, gives enough power, and lasts a long time.

Exam Tip: When defining a good energy source, mention convenience, steady supply, and long-term availability as key criteria.

 

Question 4. What is a fuel?
Answer: Fuel is a material that, when burned, generates usable energy. Examples include wood, coal, petrol, diesel, kerosene, CNG, and LPG.
In simple words: Fuel is anything we burn to get energy, like wood or petrol.

Exam Tip: Define fuel by its primary function (producing energy by burning) and provide a few common examples.

 

Question 5. What are fossil fuels?
Answer: Fossil fuels are formed from the ancient remains of plants and animals that were buried deep underground for millions of years. These organic materials underwent intense heat and pressure, transforming them into substances like coal, oil, and natural gas. They are a primary source of energy for many industries and transportation.
In simple words: Fossil fuels are old plant and animal remains that changed into coal, oil, or gas over millions of years, giving us energy.

Exam Tip: Remember to mention both the origin (ancient organic matter) and the process (heat and pressure over millions of years) when describing fossil fuels.

 

Question 6. What is biomass?
Answer: The material found in living organisms is referred to as biomass.
In simple words: Biomass is the stuff from plants and animals that can be used for energy.

Exam Tip: Think of biomass as any organic matter derived from living or recently living organisms that can be used as an energy source.

 

Question 7. What does bio-gas consist of?
Answer: Biogas is composed of 75% methane.
In simple words: Biogas is mostly made up of methane gas, about three-quarters of it.

Exam Tip: When asked about biogas composition, remember methane is the primary component and often constitutes about three-quarters of the gas.

 

Question 8. What are the conventional sources of energy?
Answer: Conventional energy sources include fossil fuels such as coal and petroleum. These are the typical energy supplies that we commonly use.
In simple words: Traditional energy sources are things like coal and oil that we've used for a long time.

Exam Tip: Conventional sources are typically non-renewable and have been in use for a long time, forming the basis of our current energy infrastructure.

 

Question 9. What are alternative or non-conventional sources of energy?
Answer: To preserve traditional energy sources like fossil fuels, scientists are working to develop ways to use new energy options such as solar and wind power. These new options are known as alternative energy sources.
In simple words: Alternative energy sources are new ways to get power, like from the sun or wind, to save our old sources.

Exam Tip: Highlight that alternative sources are being developed to reduce reliance on conventional (often exhaustible) sources and include examples like solar, wind, and geothermal energy.

 

Question 10. Which is the ultimate source of energy?
Answer: The Sun is the final source of all energy.
In simple words: The sun is where almost all our energy comes from.

Exam Tip: Recognize the sun as the primary origin of almost all energy forms on Earth, either directly or indirectly.

 

Question 11. What is geothermal energy?
Answer: Geothermal energy refers to the heat power acquired as steam from deep within the Earth's crust. This natural warmth is a reliable energy source.
In simple words: Geothermal energy is heat from inside the Earth, often used as steam.

Exam Tip: Define geothermal energy by its source (Earth's interior) and its common form (heat or steam).

 

Question 12. Name the renewable sources of energy
Answer: Solar, wind, and water represent some renewable energy sources.
In simple words: Solar, wind, and water are types of energy that can be naturally replaced.

Exam Tip: When identifying renewable sources, think of those that replenish naturally and are not depleted by use.

 

Question 13. Name some non-renewable sources of energy
Answer: Coal and petroleum are examples of non-renewable energy sources.
In simple words: Coal and oil are non-renewable because they take too long to form again.

Exam Tip: Non-renewable sources are those that are used up faster than they can be naturally replaced, like fossil fuels.

 

Question 14. Name any two materials that are used for making solar cells.
Answer: Silicon, germanium, and selenium are materials employed in the creation of solar cells.
In simple words: Solar cells are made using materials like silicon, germanium, or selenium.

Exam Tip: Focus on common semiconductor elements like silicon as the primary material for solar cell fabrication.

 

Question 15. Name some gadgets where solar cells are used.
Answer: Solar cells find application in traffic lights, artificial satellites, and solar calculators, among other devices.
In simple words: Solar cells are in things like traffic lights, space satellites, and calculators.

Exam Tip: Think of everyday items and specialized equipment where a small, portable power source from light is beneficial.

 

Question 16. What is the minimum wind velocity required for obtaining electric power with a windmill generator?
Answer: A minimum wind speed of 15 km/h is needed to generate electric power using a windmill generator.
In simple words: Windmills need the wind to blow at least 15 kilometers per hour to make electricity.

Exam Tip: Remember the specific wind speed threshold (15 km/h) required for efficient electricity generation by windmills.

 

Question 17. What is the range of temperature that can be obtained in a box-type solar cooker?
Answer: A box-type solar cooker can achieve temperatures ranging from 100°C to 140°C.
In simple words: A box-style solar cooker can heat up to between 100 and 140 degrees Celsius.

Exam Tip: Recall the typical temperature range for box-type solar cookers, noting it's sufficient for cooking but not extremely high heat applications.

 

Question 18. What fraction of solar energy reaches the earth's surface?
Answer: Approximately half of the solar energy emitted by the Sun reaches the Earth's surface.
In simple words: Roughly half of the sun's energy gets to the Earth's ground.

Exam Tip: Remember that a significant portion of solar radiation is absorbed or reflected by the atmosphere before reaching the ground.

 

Question 19. What is the value of solar constant on earth?
Answer: The value of the solar constant on Earth is \( 1.4 \, \text{kW/m}^2 \).
In simple words: The solar constant tells us how much sun energy hits one square meter of Earth's atmosphere per second, which is 1.4 kilowatts.

Exam Tip: Ensure you state the correct value (1.4 kW/m²) and its units for the solar constant.

 

Question 20. What is the age of the sun?
Answer: The Sun is approximately 5 billion years old and is expected to continue its lifespan for another 5 billion years.
In simple words: The sun is about 5 billion years old and will keep shining for another 5 billion years.

Exam Tip: Remember both the current age and the estimated remaining lifespan of the Sun are roughly 5 billion years each.

 

Question 21. Name some devices that can harness solar energy
Answer: Devices that can capture solar energy include solar cookers, solar cells, and solar water heaters.
In simple words: Things like solar cookers, solar cells, and solar water heaters can use the sun's energy.

Exam Tip: List practical applications that directly convert solar radiation into heat or electricity.

 

Question 22. Name one liquid and one gaseous fossil fuel.
Answer: Petrol is a liquid fossil fuel, while natural gas is a gaseous fossil fuel.
In simple words: Petrol is a liquid fossil fuel, and natural gas is a gas fossil fuel.

Exam Tip: Differentiate between the physical states of common fossil fuels when answering this type of question.

 

Question 23. Name the process that produces such a large amount of energy in the sun.
Answer: The process responsible for generating such a vast amount of energy in the Sun is nuclear fusion.
In simple words: The sun makes a lot of energy through a process called nuclear fusion.

Exam Tip: Recall that the sun's energy comes from the fusion of hydrogen atoms into helium, not fission.

 

Question 24. What is a renewable source of energy?
Answer: A renewable energy source is one that can be acquired consistently, even with continuous use. Examples include solar, wind, and water energy.
In simple words: Renewable energy is power that we can keep getting because it naturally refills itself, like sun or wind.

Exam Tip: Define renewable sources by their ability to replenish naturally and avoid depletion, citing common examples.

 

Question 25. What is a non-renewable source of energy?
Answer: A non-renewable energy source is one that exists in a limited amount and takes millions of years to form again. Once these sources are used up, they cannot be quickly replaced.
In simple words: Non-renewable energy is limited and takes a very long time to form, so it runs out when used.

Exam Tip: Emphasize the finite nature and extremely slow regeneration time as key characteristics of non-renewable energy sources.

 

Question 26. Name a device used to harness wind energy.
Answer: A windmill is a device employed to capture wind energy.
In simple words: A windmill is used to catch wind and turn it into power.

Exam Tip: Identify the windmill as the primary device for converting wind's kinetic energy into mechanical or electrical energy.

 

Question 27. What is wind energy farm?
Answer: A wind energy farm is a vast, concentrated area where many windmills are constructed, and their generated energy is connected together.
In simple words: A wind farm is a big place with many windmills that work together to make electricity.

Exam Tip: Emphasize that a wind farm is a collection of windmills in one area, working collectively to produce power on a larger scale.

Short Answer Type Questions

 

Question 1. What raw materials can be used in a biogas plant to produce biogas?
Answer: The basic materials suitable for biogas production include cow dung, vegetable waste, sewage, and agricultural residues.
In simple words: We can use cow dung, plant waste, sewage, and farm waste to make biogas.

Exam Tip: List common organic wastes like animal dung and plant matter as primary inputs for biogas generation.

 

Question 2. What is the use of the slurry left behind in the biogas plant?
Answer: The slurry remaining after biogas generation serves as manure, being highly rich in nitrogen and phosphorus nutrients.
In simple words: The leftover slurry from biogas making is good for fertilizing plants because it has lots of nitrogen and phosphorus.

Exam Tip: Highlight the value of biogas slurry as a nutrient-rich organic fertilizer for agriculture.

 

Question 3. Name the places where nuclear reactors are located in India.
Answer: Nuclear power reactors are situated in these locations across India:
• Tarapur (Maharashtra)
• Kalpakkam (Tamil Nadu)
• Kota (Rajasthan)
• Kakrapar (Gujarat)
• Kaiga (Karnataka)
In simple words: India has nuclear reactors in places like Tarapur, Kalpakkam, Kota, Kakrapar, and Kaiga.

Exam Tip: Be sure to list at least three to four major operational nuclear power plant locations in India, along with their respective states, to score full marks.

 

Question 4. How much energy needs of our country and the world is being fulfilled by nuclear power?
Answer: In India, merely 3% of the total electricity generation originates from nuclear power facilities. In contrast, industrialized nations typically acquire about 30% of their electrical power from nuclear plants.
In simple words: India gets only 3% of its electricity from nuclear power, but many developed countries get about 30% from it.

Exam Tip: Remember the significant difference in nuclear power contribution between India (low percentage) and industrialized countries (higher percentage).

 

Question 5. Why are fossil fuels classified as non-renewable sources of energy?
Answer: Fossil fuels required millions of years to develop beneath the Earth's surface, so their quantity is limited. If we continue consuming them at the current rate, we will quickly deplete our energy supply. Because they cannot be replenished quickly, they are termed non-renewable energy sources.
In simple words: Fossil fuels are non-renewable because they took millions of years to form and there's a limited supply; we use them faster than they can be made again.

Exam Tip: Key points for this explanation are the long formation time, finite supply, and inability to replenish quickly, leading to eventual depletion.

 

Question 6. What is the principle of solar cookers? Name two types of solar cookers.
Answer: Solar cookers utilize the Sun's heat energy. They function by creating a greenhouse effect with black surfaces and a glass cover when exposed to sunlight. The two main varieties of solar cookers are the box type and the concentrator type.
In simple words: Solar cookers use the sun's heat and a greenhouse effect to cook food. The two main kinds are box cookers and concentrator cookers.

Exam Tip: When explaining solar cooker principles, mention both the greenhouse effect and the use of black surfaces, and clearly state the two primary types.

 

Question 7. What is the output of a solar cell?
Answer: A standard solar cell generates a voltage ranging from 0.55 to 1 V and can yield approximately 0.7 W of electricity when illuminated by the sun.
In simple words: A solar cell gives out about 0.55 to 1 volt of power and around 0.7 watts of electricity when sunlight hits it.

Exam Tip: Remember to specify both the typical voltage range (0.55-1 V) and the power output (around 0.7 W) for a solar cell.

 

Question 8. Name the different constituents of biogas.
Answer: Biogas is primarily composed of methane (approximately 75%). Other important gases present include carbon dioxide, hydrogen, and hydrogen sulfide.
In simple words: Biogas is mostly methane, but also has carbon dioxide, hydrogen, and hydrogen sulfide.

Exam Tip: When listing biogas components, always start with methane as the main gas, and include carbon dioxide as the second largest component.

 

Question 9. How does a solar panel light up a bulb at night when there is no solar energy?
Answer: Electricity produced by a solar panel during daylight hours is used to charge the storage batteries. These batteries then power an inverter system at night, which delivers alternating current to illuminate the bulb.
In simple words: Solar panels charge batteries in the day. At night, the batteries use an inverter to power the bulb.

Exam Tip: Explain the energy storage (batteries) and conversion (inverter) mechanisms that allow solar power to be used after sunset.

 

Question 10. Why is bio-gas called a clean fuel?
Answer: Biogas is considered a clean fuel for several reasons:
• It burns without leaving any residue.
• It can be directly employed for heating, lighting, and other uses.
• It does not generate any toxic gases.
In simple words: Biogas is clean because it burns without ash, can be used directly for many things, and doesn't make poisonous fumes.

Exam Tip: Focus on the lack of harmful emissions (ash, poisonous gases) and direct usability as key arguments for biogas being a clean fuel.

 

Question 11. Give reasons why hydrogen can not be used as a domestic fuel?
Answer: Despite its high calorific value, hydrogen cannot be employed as a household fuel because of its explosive nature and the difficulties associated with its storage and transportation.
In simple words: Hydrogen isn't used at home because it's explosive and hard to keep and move, even though it provides a lot of heat.

Exam Tip: The main reasons are safety concerns (explosiveness) and logistical challenges (storage, transport), despite its high energy content.

 

Question 12. Name the commonly used forms of energy
Answer: The frequently utilized forms of energy include thermal energy (obtained from sources like cow dung, firewood, coal, and natural gas) and electrical energy (generated by thermal, hydroelectric, and nuclear power plants).
In simple words: We often use heat energy from things like wood and coal, and electric energy from power stations.

Exam Tip: Classify commonly used energy into thermal (with traditional sources) and electrical (with modern generation methods).

 

Question 13. What are the different types of energies obtained from the sea?
Answer: Various types of energy can be acquired from the sea:
• Tidal energy: This energy is held by the rising and falling of high and low tides.
• Wave energy: This refers to the energy contained within ocean waves.
• Ocean thermal energy: This energy is gained from the temperature difference between the surface water and deeper layers of seawater.
In simple words: We get energy from the sea through tides, waves, and the temperature difference between warm top water and cold deep water.

Exam Tip: List the three main forms of ocean energy: tidal, wave, and ocean thermal, and provide a brief explanation for each.

 

Question 14. What are the disadvantages of using a solar cooker?
Answer: The drawbacks of employing a solar cooker include:
• The cooking process is slow.
• It can only be used when sunlight is present, meaning it cannot operate on cloudy days or at night.
• Its effectiveness depends on the constant adjustment of reflectors to properly focus sunlight.
In simple words: Solar cookers cook slowly, only work when it's sunny, and sometimes need their mirrors adjusted.

Exam Tip: Key disadvantages include speed, reliance on sunlight, and the need for manual adjustment of reflectors.

 

Question 15. Describe a simple activity to demonstrate the working of a turbine generator. How does it produce electricity?
Answer: A turbine is made up of a moving assembly of blades. A flowing fluid strikes these blades, causing them to rotate and transfer energy to the rotor. As the rotor turns rapidly, it drives the shaft of a dynamo, converting mechanical energy into electrical energy.
In simple words: A turbine has blades that spin when hit by moving water or steam. This spinning motion then makes a dynamo create electricity.

with metal sheets Dynamo Bulb

Exam Tip: Clearly describe the role of moving fluid (steam/water), blades, rotor, and dynamo in converting mechanical energy to electrical energy.

 

Question 16. Explain the working of a hydroelectric power plant to produce electricity
Answer: To generate hydroelectricity, tall dams are built across rivers to block water flow and create substantial reservoirs. Water from an elevated position within the dam is then channeled through large pipes to a turbine positioned at the dam's base. These turbines are linked to an electrical generator. The spinning of the turbines causes the generator to produce electricity. The water stored at a certain height possesses significant potential energy, which transforms into kinetic energy as it flows down and strikes the turbines. This kinetic energy then becomes the mechanical energy of the turbine, ultimately converted into electrical energy by the generator.
In simple words: Hydroelectric plants make electricity by holding water behind a dam. When the water falls from a height, it spins a turbine, which then makes a generator produce power.

Exam Tip: Explain the energy transformation sequence: potential energy of stored water → kinetic energy of flowing water → mechanical energy of turbine → electrical energy from generator.

 

Question 17. Describe how a solar cell is fabricated? Name two elements used for fabricating it. What is a solar cell panel?
Answer: To fabricate solar cells, various semiconductors such as arsenic and silicon are utilized. Silicon sheets are attached to arsenic and linked with silver wires. Two typical elements employed are selenium and germanium, or arsenic and silicon. A solar cell panel comprises numerous individual cells connected to each other to generate a substantial quantity of electricity.
In simple words: Solar cells are made using semiconductors like silicon and arsenic, connected with wires. A solar panel is just many of these cells joined to make more power.

Exam Tip: Include the semiconductor materials (silicon, germanium, arsenic), the connection method (silver wires), and explain that a panel is an array of cells for higher output.

 

Question 18. Draw a diagram and explain the construction and working of a box-type solar cooker.
Answer: Construction:
• Use a metal box and paint it black.
• Place a glass sheet on the top of the box.
• A concave mirror or a plane mirror can be used for reflection.

Working:
The black box effectively absorbs the heat. The mirror directs the sun's rays to a concentrated point within the box. The glass sheet produces a greenhouse effect by permitting all the heat radiation to enter the box after reflection. Once inside, these radiations cannot easily escape, which increases the temperature inside the box.
In simple words: A solar cooker is a black box with a glass lid and a mirror. The mirror sends sun rays into the box, the black color soaks up heat, and the glass keeps it trapped inside, making it hot enough to cook.

Exam Tip: For the diagram, ensure labels for the mirror, glass sheet, black box, and sun rays are clear. For working, explain the roles of heat absorption, reflection, and the greenhouse effect.

 

Question 19. Write three advantages of nuclear energy
Answer: Nuclear energy offers three key benefits:
(a) It demonstrates very high efficiency; even a tiny quantity of nuclear fuel can generate a significant amount of heat energy, which can be managed and utilized.
(b) It does not emit any harmful gases, such as \( \text{SO}_2 \), \( \text{CO}_2 \), or \( \text{NO}_2 \), into the atmosphere, which might otherwise lead to acid rain or contribute to the greenhouse effect.
(c) Once the reaction begins, it can continue autonomously for many decades unless intentionally halted.
In simple words: Nuclear energy is very efficient, doesn't pollute the air with harmful gases, and can run for a very long time once started.

Exam Tip: Focus on high energy yield from a small amount of fuel, minimal air pollution (no greenhouse gases/acid rain contributors), and long operational periods as main advantages.

 

Question 20. Name three forms in which energy from the ocean is made available for use. What are the OTEC power plants? How do they operate?
Answer: Energy from the ocean can be obtained in three primary forms:
• Wave energy
• Tidal energy
• Ocean thermal energy

OTEC stands for Ocean Thermal Energy Conversion. These power plants can function effectively if the temperature difference between the surface water and water at depths up to 2 km is 293 K (\( 20^\circ \text{C} \)) or greater. The warmer surface water is used to heat a volatile liquid, such as ammonia, causing it to boil and produce vapor. This vapor then drives a turbine. Subsequently, colder water from the ocean's depths is pumped up to condense the vapor back into a liquid, completing the cycle.
In simple words: Ocean energy comes from waves, tides, and temperature differences. OTEC plants use the temperature gap between warm surface water and cold deep water to boil a liquid, make steam, turn a turbine, and then cool the steam back down.

Exam Tip: Clearly list the three forms of ocean energy. For OTEC, explain the principle of using temperature differences to vaporize and condense a working fluid, which then drives a turbine.

 

Question 21. The current generation should focus on making of all the devices and equipment which shall work only on renewable sources of energy Explain why.
Answer: The present generation should concentrate on developing devices and equipment that operate solely on renewable energy sources for several reasons:
• Global warming is reaching critical levels, and environmental conditions are rapidly altering.
• Fossil fuels are being depleted, making the necessity for alternative fuels undeniable.
• Most developed nations have already transitioned to using renewable energy sources.
• Advances in technology have significantly boosted the efficiency of solar panels, windmills, and biogas systems.
In simple words: We should use more renewable energy because global warming is bad, fossil fuels are running out, developed countries are already doing it, and green technology is now much better.

Exam Tip: Justify the shift to renewables by citing environmental concerns (global warming), resource scarcity (fossil fuel depletion), global trends, and technological improvements.

 

Question 22. What are the initiatives taken by our government in encouraging people to use alternative sources of energy?
Answer: Our government has implemented several initiatives to encourage the public to adopt alternative energy sources. These include offering numerous subsidies and simplifying the import process for relevant technologies.
In simple words: The government gives money help (subsidies) and makes it easier to bring in green energy tech to get people to use alternative energy.

Exam Tip: Mention government actions like providing subsidies and relaxing import regulations to promote the adoption of alternative energy technologies.

 

Question 23. Name a few states that have mum installation f solar panels in India.
Answer: Some states in India with significant solar panel installations include Maharashtra, Gujarat, Karnataka, and Tamil Nadu.
In simple words: States like Maharashtra, Gujarat, Karnataka, and Tamil Nadu have many solar panels installed.

Exam Tip: When asked to name states, provide at least three or four examples of those with notable solar energy infrastructure.

 

Question 24. The use of technology can solve the problems of global warming. Justify this statement.
Answer: If technology is applied appropriately to research and discover the most effective renewable energy sources and devices, it will undeniably reduce our reliance on fossil fuels. This will also decrease the emission of carbon dioxide gas, leading to a reduction in greenhouse gas releases, thereby allowing the problem of global warming to be tackled effectively.
In simple words: With smart technology, we can find better ways to use renewable energy, reducing how much fossil fuel we burn. This will lower carbon emissions and help fix global warming.

Exam Tip: Emphasize how technological advancements in renewable energy research and development can directly lead to reduced fossil fuel consumption and lower greenhouse gas emissions.

 

Question 25. Air pollution in Delhi during winters is due to the burning of agricultural waste as one of the reasons. Explain how this problem can be addressed.
Answer: Air pollution in cities like Delhi during winter is partly caused by the burning of farm waste. This issue can be tackled through joint efforts by local communities and the government. Villagers can be educated about converting agricultural waste into biogas. The government could establish biogas plants for farmers or compensate them for their waste, thus promoting its use for biogas production instead of burning.
In simple words: To stop winter air pollution from burning farm waste, local people and the government should teach villagers to make biogas from waste instead of burning it, maybe even paying them for it.

Exam Tip: Focus on community involvement and government initiatives, specifically converting agricultural waste into biogas, as a sustainable solution to this environmental problem.

 

Question 26. India has the potential of producing a large amount of energy -from renewable sources of energy Justify
Answer: India possesses significant potential for generating substantial energy from renewable sources due to several factors. The country features an extensive coastline, and most states experience ample sunlight throughout the year. This long coastline is suitable for establishing tidal power plants, and consistent coastal winds allow for the installation of numerous wind farms. Given the continuous availability of sunlight, solar panels are highly effective for producing renewable energy. Additionally, India has nuclear resources that can be utilized in nuclear power plants to generate electricity.
In simple words: India can make a lot of renewable energy because it has a long coast for wind and tidal power, lots of sunshine for solar panels all year, and nuclear resources for electricity.

Exam Tip: Highlight geographical advantages like long coastlines, abundant sunlight, and wind resources, as well as the presence of nuclear resources, to justify India's renewable energy potential.

 

Question 27. "I want to use alternative sources of energy but when I go to the market I don't easily get the solar lamps, solar cookers, and solar water heaters." This is what citizens in India said when I asked about the switching to alternative sources of energy Give the solutions to this issue.
Answer: Indeed, it is true that devices relying on alternative energy sources are not readily accessible. To address this, India's youth should establish startups to make these products available directly to consumers. Concurrently, manufacturing facilities should be built, and young people should receive training in the skills needed to produce and maintain these renewable energy devices. This approach could also create many employment opportunities for our citizens.
In simple words: Since green energy devices aren't easy to find, young people should start businesses to sell and make them, and also get trained to fix them. This will also create jobs.

Exam Tip: Propose solutions focusing on improving accessibility (startups, manufacturing) and capacity building (training youth) to overcome barriers to alternative energy adoption.

Long Answer Type Questions

 

Question 1. Explain the structure and working of a fixed dome biogas plant.
Answer: A fixed dome biogas plant features a brick-built, dome-shaped structure. A mixture of cow dung and water, called slurry, is prepared in a mixing tank and then transferred into a sealed, underground depositor. This digester acts as an airtight chamber where oxygen is absent. Anaerobic microbes then decompose the intricate compounds within the slurry. This process yields a mixture of gases, including methane, carbon dioxide, hydrogen, and hydrogen sulfide. The biogas is accumulated in a gas tank situated above the digester, from where it is extracted through pipes for consumption.
In simple words: A biogas plant has a brick dome where cow dung and water (slurry) go into a sealed tank. Tiny germs break down the slurry without air, making gases like methane. This biogas is then stored and used through pipes.

Exam Tip: Describe the process clearly from slurry preparation, anaerobic digestion in the digester, gas formation, to its collection and use, supported by a well-labeled diagram.

 

Question 2. (a) What is nuclear energy? (b) What are the main hazards of nuclear power generation? (c) What are the advantages of nuclear energy?
Answer:
(a) Nuclear energy is defined as the energy generated through either nuclear fission or nuclear fusion reactions.
(b) The primary risks associated with nuclear power generation include the accumulation of spent fuels, as uranium undergoes decay and emits dangerous radiation. Inadequate storage and disposal of nuclear waste lead to environmental contamination.
(c) The benefits of nuclear energy include its ability to release an enormous amount of energy from a small quantity of nuclear fuel. Additionally, the self-sustaining nuclear fission reaction can be carefully managed to provide the precise amount of energy needed.
In simple words: (a) Nuclear energy comes from splitting or joining atoms. (b) Big dangers are radioactive waste and pollution if not handled right. (c) Its advantages are huge energy from little fuel and controllable reactions.

Exam Tip: For nuclear energy, define it by fission/fusion, list hazards like radioactive waste and contamination, and mention advantages such as high energy output and controlled reactions.

Questions On Higher Order Thinking Skills (Hots)

 

Question 1. A person 'X' rolled up the glasses of his black car and parked it in sun for one hour. Another person 'Y' rolled up-te glasses of a white car and parked it in sun for one hour. in which car will the temperature inside the car be more and why?
Answer: The temperature inside the black car will be higher because black color absorbs more heat. Furthermore, the car's glass windows create a greenhouse effect, which traps the absorbed heat and further raises the internal temperature.
In simple words: The black car will be hotter because dark colors soak up more sun heat, and the windows trap that heat inside, making it even warmer.

Exam Tip: Explain both the principle of color absorption (black absorbs more) and the greenhouse effect (glass traps heat) to fully answer why the black car gets hotter.

 

Question 2. Suggest any three ways to contribute to saving LPG/CNG at home.
Answer: Here are three ways to help save LPG/CNG at home:
• Pre-soak lentils and rice in water before cooking; this reduces cooking time and fuel consumption.
• Frequently use a pressure cooker for meals.
• Always cover the container with a lid while cooking.
In simple words: To save cooking gas, soak grains before cooking, use a pressure cooker often, and always put a lid on your cooking pots.

Exam Tip: Focus on methods that reduce cooking time and heat loss, such as pre-soaking, using a pressure cooker, and covering utensils.

 

Question 3. A student wants to design a car which can run on any alternative source of energy Suggest any two sources of energy and give its advantages.
Answer:

• Solar cells panel - these can be installed on the rooftop of the car. They can change the sun's energy into electrical power, charge the car's battery, and run the vehicle.
• Use water as a fuel that can split into \( H_{2} \) and \( O_{2} \) gas, and the \( H_{2} \) gas produced can then be burned to run the engine.

Exam Tip: When suggesting alternative energy sources, always provide specific examples and clearly explain how they can power the car, mentioning key benefits.

 

Question 4. During summers the houses on the top floor get heated, even the classes on the top floor get equally heated. Suggest a few methods by which you can overcome this problem.
Answer:

• Using insulators like thermocol can be fixed on the room's ceiling. This acts as an insulator and stops outside heat from entering the room.
• If windows have clear glass, they should be covered with sun film reflector.
• On the rooftop, trap the air by placing inverted pots or planting small trees all over the roof.

Exam Tip: Focus on methods that either block heat transfer (insulators, reflectors) or absorb/dissipate heat (plants) to effectively address overheating issues.

 

Question 5. Do you have to design a hydroelectric power plant model in which you have to produce electricity How will you complete this project? 1. Name the fuel/source of energy you will use to produce electricity.
Answer: To design a power plant model to produce electricity, we need to use:

1. Water
2. Generator, turbine, pipes, water moving with speed.

In simple words: To make a model of a power plant that makes electricity, you'd use water, plus a generator, turbine, and pipes to move the fast-flowing water.

Exam Tip: When describing a hydroelectric power plant, always mention the key components: water, dams, pipes, turbines, and generators, and how they interact to produce electricity.