SEE science notes
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?
Ans: 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.
Ans: Differences between renewable and non-renewable source
of energy are.
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.
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