NCERT Solutions Class 10 Science
The NCERT Solutions in English Language for Class 10 Science Chapter – 14 (Sources of Energy) has been provided here to help the students in solving the questions from this exercise.
Chapter – 14 (Sources of Energy)
Questions
1. What is good source of energy ?
Answer – A substance which produces sufficient amount of energy over a long period of time without producing much smoke is known as good source of energy. Characteristics of a good source of energy.
2. What is good fuel ?
Answer – A fuel which provides large amount of heat energy without causing pollution.
3. If you could use any source of energy for heating your food, which one would you use and why ?
Answer – We would use microwave oven for heating our food. This is because the nutritional value of food is not lost when heated in a microwave oven.
Questions
1. What are the disadvantages of fossil fuels ?
Answer – There are following disadvantage of fossil fuels:
- Burning of fossil fuels causes’ pollution.
- Oxides of Sulphur and nitrogen produced on burning of fossil fuel causes acid rain.
- Carbon dioxide causes greenhouse effect.
- Fossil fuels are non-renewable sources of energy.
2. Why are we looking at alternate sources of energy ?
Answer – Because the conventional sources of energy may completely be exhausted one day if their use at the present rate continues.
3. How has the traditional use of wind energy and water been modified for our convenience
Answer – Traditional use of wind and water energy have been modified in the following ways:
- Wind energy : Through windmill-Windmill can be used for running water pump, grinding grains and generating electricity.
- Water energy : Through the use of hydro energy, by constructing dams and setting up hydroelectric power stations.
Questions
1. What kind of mirror—concave, convex or plane would be best suited for the use in a solar cooker. Why ?
Answer – Concave mirror, because it focusses the sun rays at a point to raise the temperature at that point.
2. What are the limitations of the energy that can be obtained from oceans ?
Answer – The energy obtained from the oceans is :
- Energy from oceans is available only when high tides are in the ocean.
- Power plants used to convert ocean energy into electric energy do not operate continuously.
- Energy of ocean waves can be extracted blow all times across the ocean.
- Tidal power plants can not be installed everywhere.
3. What is geothermal energy ?
Answer – The heat energy stored in the hot spots of the earth’s crust is called geothermal energy.
4. What are the advantages of nuclear energy ?
Answer – Some advantages of nuclear energy are:
- A small quantity of nuclear fuel gives a large amount of energy.
- In a nuclear power plant, the nuclear fuel is inserted once to get energy over a longer period of time.
Questions
1. Can any source of energy be pollution free ? Why or why not ?
Answer – No source of energy is there which is pollution free. However, some sources of energy cause more pollution and some sources of energy cause less pollution.
2. Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not ?
Answer – Hydrogen is a cleaner fuel than CNG. This is due to the reason that it produces water on burning whereas CNG on burning produces CO2, though much less than that produced when coal or oil is burnt. The increase in concentration of CO2 in the atmosphere increases the temperature of atmosphere.
Questions
1. Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer – Two renewable sources of energy are as follows:
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Sun : The energy derived from the Sun is known as solar energy. Solar energy is produced by the fusion of hydrogen into helium, fusion of helium into other heavy elements, and so on. A large amount of hydrogen and helium is present in the Sun. Therefore, solar energy can replenish on its own. The Sun has 5 billion years more to burn. Hence, solar energy is a renewable source of energy.
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Wind : Wind energy is derived from air blowing with high speed. Wind energy is harnessed by windmills in order to generate electricity. Air blows because of uneven heating of the Earth. Since the heating of the Earth will continue forever, wind energy will also be available forever.
2. Give the names of two energy sources that you would consider to be exhaustible.
Answer – Coal and petroleum are two exhaustible sources of energy. These fuels were formed over million for years ago and there are only limited reserves. If we continue to use them as at present, these reserves will be exhausted soon.
Exercises
1. A solar 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
2. Which of the following is not a example of a bio-mass energy source ?
(a) wood,
(b) gobar gas,
(c) fossil fuels,
(d) bio-mass.
Answer – (c) fossil fuels
3. Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Suns energy ?
(a) geothermal energy,
(b) wind energy,
(c) fossil fuels,
(d) bio-mass.
Answer – (a) geothermal energy
4. Compare and contrast fossil fuels and the Sun as a source of energy.
Answer –
| Fossil Fuel | Energy from Sun |
| Non-renewable source of energy. | Renewable source of energy. |
| Causes pollution in the environment. | Does not cause any pollution in the environment. |
| Produces large amount of energy. | Produces relatively less amount of energy. |
| Less amount of land is required to set up a power plant running on fossil fuels. | Huge space is required to generate substantial amount of energy by solar panels. |
5. Compare and contrast bio-mass and hydro-electricity as source of energy.
Answer –
| Bio-mass | Hydro Electricity |
| Biomass is a renewable energy source. |
Hydroelectricity is also is a renewable energy source. |
| Dead plants and animal wastes are used to create biomass. Hence, it is replenished organically. | It is produced by utilizing the potential energy contained in water at a height. |
| Burning of biomass by causes air pollution | The use of hydroelectricity does not cause any pollution. |
| Biomass gives off heat energy, which can be used for cooking. | Hydroelectricity can run all types of electric appliances. |
| Biomass energy can be obtained without using any special devices. | Hydroelectricity can be produced only by establishing hydropower plants. |
6. What are the limitations of extracting energy from
(a) the wind
(b) Waves
(c) Tides ?
Answer –
(a) Wind energy is harnessed by windmills. One of the limitations of extracting energy from wind is that a windmill requires wind of speed more than 15 km/h to generate electricity. Also, a large number of windmills are required, which covers a huge area.
(b) Very strong ocean waves are required in order to extract energy from waves.
(c) Very high tides are required in order to extract energy from tides. Also, occurrence of tides depends on the relative positions of the Sun, moon, and the Earth.
7. On what basis you classify energy source as
(a) Renewable and non-renewable ?
(b) Exhaustible and inexhaustible ?
(c) Are the options given in (a) and (b) the same ?
Answer –
(a) Renewable sources of energy are those sources which can be regenerated again. Non-renewable sources of energy are those sources which would get depleted some day and cannot be regenerated.
(b) Exhaustible sources of energy are those which will be exhausted some day and cannot be regenerated. Inexhaustible sources of energy are those which can be regenerated again due to some continuing or repetitive currents of energy and are inexhaustible.
Options in both cases are exactly same.
8. What are qualities of an ideal source of energy ?
Answer – The qualities of ideal sources of energy are:
- It supplies useful energy continuously.
- It does not cause environment pollution.
- It is economical.
9. What are the advantages and disadvantages of using a solar cooker ? Are there places where solar cookers would have limited utility ?
Answer –
Advantage of solar cooker :
- There is no cost of fuel.
- It is environment friendly and there is no residue like ash etc.
- Cooking is hygienic and nutritious.
Disadvantage of solar cooker :
- The cooking is slow.
- It cannot be used at all times.
- A solar cooker can perform only limited functions.
10. What are the environmental consequences of the increasing demand for energy ? What steps would you suggest to reduce energy consumption ?
Answer – Industrialization increases the demand for energy. Fossil fuels are easily accessible sources of energy that fulfil this demand. The increased use of fossil fuels has a harsh effect on the environment. Too much exploitation of fossil fuels increases the level of greenhouse gas content in the atmosphere, resulting in global warming and a rise in the sea level. It is not possible to completely reduce the consumption of fossil fuels. However, some measures can be taken such as using electrical appliances wisely and not wasting electricity. Unnecessary usage of water should be avoided. Public transport system with mass transit must be adopted on a large scale. These small steps may help in reducing the consumption of natural resources and conserving them.
