NCERT Science Class 10 Chapter 15 Sources of Energy CBSE Board Sample Problems Very Short Answer

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Question

The wind velocity at three places A, B and C are 5Km/hr, 1 5Km/hr, 1 0Km/hr respectively. Which is the most suitable place for installing wind mill & why?

Solution

B, Maximum velocity required is 15km/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 ¡s 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 ¡s 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.