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NCERT Science Class 10 Chapter 15 Sources of Energy CBSE Board Sample Problems Very Short Answer
Question
The wind velocity at three places A, B and C are 5 Km/hr, 1 5 Km/hr, 1 0 Km/hr respectively. Which is the most suitable place for installing wind mill & why?
Solution
B, Maximum velocity required is 15 km/h. At lower speed it will not work. At very high speed it may break the blades.
Question
Mention any two reasons, why wood is not preferred as fuel.
Solution
- Burning wood cause՚s pollution
- Excess use of wood would cause deforestation
Question
Consider two solar cooker, one covered with a plane glass plate and other kept open. Which of the two cooker would be more efficient and why?
Solution
Solar cooker with covered glass slab, as it will show greenhouse effect.
Question
Give one reason how increasing dependence on nuclear power generation is a threat for future generation?
Solution
Radiation emitted during leakage can change the genetic arrangement or disposal to nuclear waste.
Question
Define anaerobic degradation.
Solution
The decomposition which takes place in the absence of oxygen by anaerobic bacteria is called anaerobic degradation.
Question
Name the gases that are generated in a biogas plant.
Solution
The gases that are generated in a biogas plant are methane, carbon dioxide, hydrogen and hydrogen sulphide.
Question
Which is the ultimate source of energy?
Solution
Sun is the ultimate source of energy.
Question
Why does acid rain happen?
Solution
- Acid rain happens because burning of fossil fuels releases oxides of carbon, nitrogen and sulphur in the atmosphere.
- These oxides with rain fall as acid rain.
Question
Write the name of the main constituent of biogas. Also state its percentage?
Solution
The main constituent of biogas is methane (75%) .
Question
Why is biogas considered as excellent fuel?
Solution
Biogas is considered as excellent fuel because it burns without smoke and leaves no residue like ash in wood, charcoal and coal burning.
Question
Suggest any two reasons which make the large scale usage of nuclear energy prohibitive
Solution
High cost of installation of a nuclear power plant and problems of safe disposal of nuclear waste are two main reasons
Question
Which of the following gases is the major constituent of bio gas. Carbon monoxide, hydrogen, methane, carbon dioxide
Solution
Methane Gas
Question
Name any two renewal sources of energy
Solution
Solar energy, wind energy, ocean wave energy, bio mass energy etc.
Question
What are conventional source of energy?
Solution
Conventional sources of energy are the natural energy resources which are regularly used for many years and are accepted as fuel to produce heat, light, food and electricity.
Question
Mention the purpose of blackening the interior of a solar cooker.
Solution
Black surface absorb more heat radiation of incident solar energy compared to other colored surface.
Question
Name any two materials used for making solar cells.
Solution
Silicon and Germanium/Selenium
Question
Why bio gas is considered an excellent fuel?
Solution
- Burns without smoke
- leaves no residue
Question
What energy transformation occurs in a hydro power plant?
Solution
In hydro power plant potential energy possessed by stored water is converted into electrical energy.
Question
Why does acid rain happen?
Solution
- Acid rain happens because burning of fossil fuels releases oxides of carbon, nitrogen and sulphur in the atmosphere.
- These oxides with rain fall as acid rain.
Question
Name any two forms of energy in which solar energy manifests itself in oceans.
Solution
- Tidal energy
- Ocean thermal energy
- Wave energy (Any two)
Question
Which is the main constituent of biogas?
Solution
The main constituent of biogas is methane (75%)
Question
The following questions consists of two statements – Assertion (A) and Reason (R) . Answer these questions selecting the appropriate option given below:
A. Both A and R are true and R is correct explanation of A.
B. Both A and R are true and R is not correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.
Assertion (A) : Solar cooker is painted white from inside.
Reason (R) : The black surface of solar cooker is better heat absorber than a white surface.
Solution
D
Question
Solar cell panels used in satellites to supply energy cannot be used to meet our domestic requirements. Explain Why? (1)
Solution
- The electricity (dc) produced by solar cell panels is stored by charging dc batteries which can be used.
- Only to operate dc devices. To operate any ac device, this dc must be first converted into ac by using converters.
- The efficiency of energy conversion is low as compared to other methods of generating electricity.