GetStudySolution


Getstudysolution is an online educational platform that allows students to access quality educational services and study materials at no cost.

NCERT Solutions for class 10 Science chapter 14 – Sources of Energy

Back Exercise

Question 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

Question 2.
Which of the following is not a example of a bio-mass energy source ?
(a) wood
(b) gobar gas
(c) Nuclear energy
(d) coal
Answer:
(c) Nuclear energy

Question 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) Nuclear energy
(d) bio-mass
Answer:
(c) Nuclear energy

Question 4.
Compare and contrast fossil fuels and the Sun as a source of energy.
Answer:

  1. Fossils fuels are the non-renewable sources of energy. On the other hand, sun is a renewable source of energy.
  2. Fossil fuels cause pollution but solar energy does not cause pollution.
  3. Energy is supplied by fossil fuels at any time of the day but sun supplies energy only when it shines.

Question 5.
Compare and contrast bio-mass and hydro-electricity as source of energy.
Answer:

Bio-mass

Hydro electricity
(i)    The energy supplied by the burning of bio-mass causes pollution.

(ii)    The energy from bio-mass can be obtained by burning it directly or by a gobar gas plant.

 (i)     Hydro-electricity does not cause pollution.

(ii)    Hydro-electricity can be obtained by constructing costly dams.

Question 6.
What are the limitations of extracting energy from
(a) the wind
(b) Waves
(c) Tides ?
Answer:
(a)We cannot depend upon wind energy as it is available only when strong wind blows. The appliances or machines operating with wind energy stop working as soon as wind stops. The minimum speed of wind to operate generator to produce electricity is 15 km/h.
(b) In order to extract energy from the waves, very strong ocean waves are needed.
(c) In order to extract energy from the tides, the sun, the moon and the earth should be in a straight alignment and the tides should be very strong.

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

Non-renewable energy sources are those which do not replenish on their own and have limited availability in nature. Like fossil fuels which includes petroleum, coal and natural gas.

b) Exhaustible and inexhaustible:
Exhaustible source of energy are those which deplete after few hundred years. Like coal and petroleum.

Inexhaustible source of energy are those which do not deplete and are available in abundant quantity. Like solar and wind energy.

c) Yes options given in (a) and (b) are same

Question 8.
What are qualities of an ideal source of energy ?
Answer:

  1. It supplies useful energy continuously.
  2. It does not cause environment pollution.
  3. It is economical.

Question 9.
What are the advantages and disadvantages of using a solar cooker ? Are there places where solar cookers would have limited utility ? (CBSE 2010)
Answer:
Advantages:

  1. There is no cost of cooking food in a solar cooker.
  2. No pollution is caused when food is cooked in a solar cooker.
  3. Nutrition value of food is preserved when food is cooked in the solar cooker.
  4. Two or three dishes can be cooked at a time.

Disadvantages:

  1. Food cannot be cooked at night and on a cloudy day using a solar cooker.
  2. The cost of making solar cooker is high.
  3. Food cannot be cooked quickly with the solar cooker.
  4. Large quantity of food cannot be cooked with a solar cooker.
  5. Chapatis cannot be made with solar cooker.
    Solar cooker will have limited utility at places where the sun shines for shorter period of time or where the sun rays never reach.

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

  1. More use of fossil fuels for fulfilling the increasing demand for energy is polluting air (i.e. the environment),
  2. LPG and CNG are considered as clean fuels but the extraction and transportation of these fuels cause environmental pollution.
  3. The use of large number of sources of energy is causing global warming.

Suggestions:

  1. Burning fuels must be extinguished as soon as their use is over.
  2. Bulbs, tubes and other electrical appliances must be switched off as soon as you leave your room.
  3. The engines of the vehicles must be switched off when these vehicles are stopped for more than a minute to save fuel.

In-Text Questions

Question 1.
What is good source of energy ?
Answer:

A good source of energy has the following properties:

Question 2.
What is good fuel ?
            Or
What is a fuel ?
Answer:
A fuel which provides large amount of heat energy without causing pollution.

Question 3.
If you could use any source of energy for heating your food, which one would you use and why ?
Answer:

For heating and cooking, natural gas can be used for the below given reasons:

Question 4.
What are the disadvantages of fossil fuels ? (CBSE 2010)
Answer:

  1. They cause environmental pollution.
  2. They cause global warming.
  3. They do not supply enough heat energy.
  4. The by-products of burning fuels cause acid rain which pollute water resources.

Question 5.
Why are we looking at alternate sources of energy ?
Answer:
The reason why we are looking at alternate sources of energy is because the fossil fuels are non-renewable sources of energy, i.e. they are not available in large quantities and cannot be replenished. Fossil fuels will get exhausted if their consumption is not controlled. Therefore, it is better to switch to alternate source of energy.

Question 6.
How has the traditional use of wind energy and water been modified for our convenience
(CBSE 2010, Term I)
Answer:

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

Similarly, waterfalls were the source of potential energy in olden days. But these days as the number of waterfalls has reduced, water dams are constructed and are used as a source to trap the potential energy. Here, the water falls from a certain height on the turbine producing electricity.

Question 7.
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.

Question 8.
What are the limitations of the energy that can be obtained from oceans ? (CBSE 2010)
Answer:

  1. Energy from oceans is available only when high tides are in the ocean.
  2. Power plants used to convert ocean energy into electric energy do not operate continuously.
  3. Energy of ocean waves can be extracted blow all times across the ocean.
  4. Tidal power plants can not be installed everywhere.
  5. The relative positioning of the earth, the sun and the moon has an impact on the tidal energy.
  6. For the conversion of tidal energy into electricity, high dams are required.
  7. To obtain electricity from wave energy, very strong waves are required.
  8. For trapping the ocean thermal energy, there should be a temperature difference of more than 20°C between hot surface water and the cold water at a depth.

Question 9.
What is geothermal energy ? (CBSE 2010, Term I, 2011, 2012)
Answer:
The heat energy stored in the hot spots of the earth’s crust is called geothermal energy.

Question 10.
What are the advantages of nuclear energy ?
Answer:

  1. A small quantity of nuclear fuel gives a large amount of energy.
  2. In a nuclear power plant, the nuclear fuel is inserted once to get energy over a longer period of time.
  3. As it does not produce any pollutants, it is clean

Question 11.
Can any source of energy be pollution free ? Why or why not ?
Answer:
No source of energy can be pollution free this is because every source of energy has leave some type of pollutants either during their use or during manufacturing.

Question 12.
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not ?
Answer:
Hydrogen causes less air pollution than C.N.G. because burning of hydrogen produces water vapours and burning of CNG produces CO2. When the concentration of CO2 increases in the atmosphere, then the temperature of the atmosphere increases. This effect is known as green house effect. The increased temperature of the atmosphere affects life on the earth.

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

  1. Bio-mass is considered as a renewable source of energy because forests can be replenished.
  2. Water is also a renewable source of energy as water is continuously available to use due to water cycle in nature.

Question 14.
Give the names of two energy sources that you would consider to be exhaustible.
Answer:
Give reasons for your choices,

  1. Coal
  2. Petroleum.

They will be exhaustible when continuously extracted. Moreover, the formation of these fuels under the earth takes a longer period of time.