SEE Science (Energy) Notes

     Energy

      




    1.  Write the name of two radioactive elements.

    Ans: The name of two radioactive elements is:                                                                                  

               a) Uranium  

               b) Plutonium                                  

               c) Radium                                                                                                                                                                    

2.   Government of Nepal encourages the farmer to establish bio gas plan. Write any two scientific reasons for it.
Ans: Government of Nepal encourages the farmer to establish bio gas plan because of following reasons:
a) Biogas burns without smoke and hence does not cause air pollution.
b) The by-product of biogas is good manure which increases the fertility of soil.
c) Biogas is cheap and renewable source of energy and can be generated easily.                                                                                                               

3.   What amount of average solar energy does the earth surface receive per square meter?
Ans: Amount of solar energy received by the earth surface per square meter per second is estimated to be 1.4 kW.

4.   Write any natural phenomena from which geothermal energy can be obtained.
Ans: Natural phenomena from which geothermal energy can be obtained are:
a) Volcano eruption
b) Earthquake

5.  Write a major disadvantage of fossil fuel.
Ans: Disadvantages of fossil fuel are:
a) Fossil fuel causes air pollution when it is burnt.
b) When petrol is brunt, harmful substances like unbrunt hydrocarbons, carbon monoxide, oxides of nitrogen, sulphur are produced. These cause acid rain and thus soil and water pollution give innumerable problem to health.

6.In fact the hydroelectricity is an indirect source of solar energy. Clarify the statement.
Ans: The heat from the sun evaporates the water from the surface of earth, from the tree leaves, ponds, rivers, oceans etc. the water vapour thus formed rises high in the atmosphere and becomes cloud. When it rains, the water vapour comes back on the earth in the form of rain, snow, hail etc. the rain water and the water formed by melting of the snow, hail, ice, etc. flow rapidly in the river and lakes which are used to produce hydroelectricity.

7.What is bio fuel?
Ans: Fuel such as methane produced from renewable biological resources such as plant biomass, animal dung, firewood, etc. is called bio fuel.

8.It is difficult to produce hydroelectricity in Nepal? Give any two reasons.
Ans: It is difficult to produce hydroelectricity in Nepal because
a) Lack of development of the modern technology and equipment.
b) Nepal is a poor country and there is lack of means, resources and skilled human resource.

9.What is the source of solar energy?
Ans: The main source of solar energy is the thermonuclear fusion reaction that continuously takes place in the sun.

10.Energy contained in fossil fuels is the outcome of solar energy, why?
Ans: Fossil fuels are obtained from remains of animals and plants under the earth over a period of millions of years. Plants get energy from sun during photosynthesis and animal get solar energy indirectly from the plants. Therefore, Energy contained in fossil fuels is the outcome of solar energy.

11.What is primary source of energy?
Ans: The natural source of energy which can be used in the natural form is called primary source of energy.

12.Write any two ways to reduce energy crisis.
Ans: Ways to reduce energy crisis are:
a) By using renewable sources of energy in place of non-renewable source of energy.
b) BY developing solar devices in place of petroleum devices.
c) By developing and using alternative energy sources.
d)  By avoiding unnecessary use of power consuming devices.
e)  By using existing sources of energy wisely and economically.

13.What.is.renewable.energy?
Ans: The energy which can be reproduced in short time and can be used continuously for long period of time is called renewable energy.                                                                                                                                                                                                                              For e.g.: Hydropower, Solar energy, Geothermal power, Wind energy, Tidal energy, Biomass energy etc.

14.  Write the differences between Deuterium and tritium.

S.N	Deuterium	S.N	Tritium
a)	It is the isotopes of hydrogen having atomic mass two.	a)	It is the isotopes of hydrogen having atomic mass three.
b)	It has one proton and one neutron.	b)	It has one proton and two neutrons.
c)	It is denoted by 1H2.	c)	It is denoted by 1H3.

15.  Write any two reasons that urbanization brings energy crisis.
Ans: The main reasons for energy crisis due to urbanization are:
a) Along with the increasing urbanization, the demand of petroleum produced has been increasing day by day to run automobiles, industries, etc. such enormous demand of energy brings energy crisis.
b)  There is misuse of non-renewable source of energy due to urbanization.

16.What is energy crisis?
Ans: The situation in which there is acute scarcity of energy sources is called energy crisis.

17.  'The use of solar energy should be increased in context of Nepal', give any two reasons to justify the statements.
Ans: The use of solar energy should be increased in context of Nepal because 
a) Solar energy is renewable source of energy and hence can be obtained continuously.
b) Being the poor country Nepal can't afford higher prices of fuels and gases.  

18.  Write any two causes of energy crisis.
Ans: Causes of energy crisis are:
a) Lack of development and use of alternative or renewable energy sources.
b) Over use of non-renewable source of energy like petroleum products.
c) High demand of energy sources due to population growth.
d)  Due to unplanned unmanaged urbanization and industrialization.

19.  What is biomass?
Ans: The waste materials of living organism (like cattle dung) and dead part of living beings (like wood, tree, sawdust, straw) are called biomass.

20.  What is LPG? Write its composition and use.
Ans: A gas liquefied by compression, consisting of flammable hydrocarbons, as propane and butane, obtained as a by-product from the refining of petroleum or from natural gas is called Liquefied Petroleum Gas (LPG).

                            Compositions of LPG are:

a)     Ethane

b)     Propane

c)     Butane

It is used as domestic fuel.

21.  What type of energy is coal? Why it is called fossil fuel?
Ans: Coal is non-renewable source of energy.

          Coals are formed from the fossilization of dead organism under the soil from millions of years. So, it is called   fossil fuel.

22.  Why more preference is given for the development of alternate source of energy in the world? Give two reasons.
Ans: More preference is given for the development of alternate source of energy in the world because
a) To reduce the rate of consumption of non-renewable source of energy like petroleum products.
b) To prevent from the energy crisis in the near future.

23.  What is fossil fuel?
Ans: The fuels which are presented in the earth crust as remains of animals and plants over a period of millions of years are called fossil fuel.
        For instant: Coal, Petrol, Natural gas, Mineral oil, etc.

24.  Why higher priority should be given for the production of hydroelectricity in the context of Nepal? Give two reasons.
Ans: Higher priority should be given for the production of hydroelectricity in the context of Nepal because:
 a) Nepal has many fast flowing rivers and perennial rivers so generation of hydroelectricity will be easy.
 b) Hydroelectricity is cheaper, long term basis, renewable and pollution free source of energy.
 c) In Nepal there is lack of mineral and petroleum substances.

25.  What is geothermal energy? Write its use.
Ans: The energy which is obtained from heat of earth core is called geothermal energy.
Uses of geothermal energy are:
a) It is used to warm the room in cold region.
b) It is used to generate electricity.

26.  Differences between nuclear fusion and fission?                                                                 

S.N	Nuclear fusion	S.N	Nuclear fission
a)	In a nuclear fusion, two light nuclei combine to form a heavy nucleus.	a)	In a nuclear fission, a heavy nucleus splits into two lighter nuclei.
b)	Nuclear fusion reactions have not been controlled so far.	b)	Nuclear fission reactions have been controlled to generate electricity.

27.  Give any two reasons that 'The sun is considered as the main source of energy'.
Ans: 'The sun is considered as the main source of energy' because
a) The sun provides the energy for all living beings on the earth directly or indirectly. We use solar energy for cooking foods, drying cloths and generating electricity. Coal, mineral, oil etc. are the outcome of the solar energy. Plant stores solar energy in the form of chemical energy. It means that plants use solar energy for the process of photosynthesis.
b) Hydro power is also an outcome of solar energy. Water in the river is either formed by melting of ice or raining. For the melting of ice, solar energy is needed. Similarly, for raining water of river and ocean must be evaporated.

28.  What is nuclear fuel?
Ans: The energy which is obtained by nuclear fusion reaction and nuclear fission reaction in atomic power-plants is called nuclear fuel.


29.  Give two reasons to justify that the use of hydroelectricity should be increased more than that of fossil fuel energy.
Ans: The use of hydroelectricity should be increased more than that of fossil fuel energy because 
a)    Hydropower is renewable source of energy but fossil fuels are non-renewable source of energy.
b)    Hydropower is pollution free source of energy but fossil fuel cause air pollution when they are used.

30.  What do you meant by alternative source of energy? Give any three alternative source of energy.
Ans: The source of energy which are used instead of non-renewable source of energy are called alternative source of energy.
For e.g.: Hydropower, Solar energy, Geothermal power, Wind energy, Tidal energy, Biomass energy etc.

31.  What is thermonuclear fusion reaction?
Ans: The reaction in which two light nuclei of light atom combine together to form a heavy nucleus with the release of tremendous amount of heat energy during nuclear reaction is called thermonuclear fusion reaction.

32.  Fossil fuel is known as non-renewable source of energy, why?
Ans: Fossil fuel is known as non-renewable source of energy because they have limited stock in nature. Once it is used up we cannot use again & again and takes millions of year to reproduce.

33.  What are the conditions of nuclear fusion reaction found in the sun?
Ans: The conditions of nuclear fusion reaction found in the sun are:
 a) There is large amount of hydrogen gas.
 b) There is high temperature and high pressure.
 c) There is huge amount of helium gas.

34.  Differences between thermonuclear fusion and fission?

Thermonuclear fission	Thermonuclear fusion
It is chain reaction.	It is not chain reaction.
It can be controlled.	It cannot be controlled.

35.  What is non-renewable energy?
Ans: The energy which cannot be reproduced in short time and cannot be used continuously for long period of time is called renewable energy.
 For instant: Fossil fuel (like coal, petroleum), Natural gases, Nuclear energy, etc.

36.  Clarify the mass-energy relation proposed by Albert Einstein.
Ans: the equation is famous equation given by Albert Einstein in his theory of relativity in 1905. This equation shows that mass of a body can be transferred into energy and vice versa. It is denoted by E = mc² where,
E = energy, m = mass and c = velocity of light.
This equation E = mc² is used to calculate the energy produced during the transformation of mass into energy.

37.  What are the three conditions required in the sun to produce enormous energy?
Ans: Any three conditions required in the sun to produce enormous energy are mentioned below: 
(i) In the sun, there is sufficient amount of hydrogen gas. 
(ii) There is presence of necessary temperature in the sun for formation of free protons. 
(iii) There is presence of necessary pressure for combination of free protons.

38.  Write the uses of hydropower.
Ans: The uses of hydropower are:
a)     It is used for generating electricity.
b)     It has multipurpose use i.e. it is used to run many types of instruments.

39.  Write down the advantages and disadvantages of nuclear energy.
Ans: Advantages of nuclear energy:
a) It is used to generate electricity.
b) It is used to treat diseases like cancer.
c) It can be used as the alternate source of energy.

        Disadvantages of nuclear energy:
    a) It causes serious health hazards due to the emission of radiation like alpha, beta, gamma etc.
    b) Nuclear energy is very expensive to establish.
    c) It pollute environment badly.

40.  Differences between renewable and non-renewable source of energy.

S.N	Renewable source of energy	S.N	Non-renewable source of energy
a)	This type of source of energy can be reproduced in short time.	a)	It takes millions of years to reproduce them.
b)	They are present in great amount.	b)	They have limited stock in nature.
c)	This type of source of energy is never depleted.	c)	This type of source of energy gets depleted.

41.  Give the name of source of energy produced by nuclear fission.

Ans: The source of energy produced by nuclear fission reaction is nuclear energy.