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NCERT Exemplar · Class 10 Science Sources of Energy

29 questions · 29 still being checked

Multiple Choice Questions 1–10 (part 1 of 4)

  1. Exercise 1

    Which of the following is a non-renewable source of energy?
    (a)
    Wood
    (b)
    Sun
    (c)
    Fossil fuels
    (d)
    Wind

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    NCERT’s answer
    (c)
    (c) Fossil fuels — coal, petroleum and natural gas took millions of years to form from buried organic matter and cannot be replenished within a human lifetime, unlike wood, the sun and wind, which renew continuously.

  2. Exercise 2

    Acid rain happens because
    (a)
    sun leads to heating of upper layer of atmosphere
    (b)
    burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere
    (c)
    electrical charges are produced due to friction amongst clouds
    (d)
    earth atmosphere contains acids

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    NCERT’s answer
    (b)
    (b) Burning fossil fuels releases oxides of sulphur and nitrogen, which combine with atmospheric moisture and oxygen to form strong acids that fall as acid rain. \[\mathrm{2SO_2 + O_2 + 2H_2O \rightarrow 2H_2SO_4} \] \[\mathrm{4NO_2 + O_2 + 2H_2O \rightarrow 4HNO_3} \]

  3. Exercise 3

    Fuel used in thermal power plants is
    (a)
    water
    (b)
    uranium
    (c)
    biomass
    (d)
    fossil fuels

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    NCERT’s answer
    (d)
    (d) Fossil fuels — coal, petroleum or natural gas are burnt to heat water into high-pressure steam that spins the turbine coupled to the generator. \[\text{fuel (chemical energy)} \xrightarrow{\text{burns}} \text{heat} \rightarrow \text{steam} \rightarrow \text{turbine} \rightarrow \text{electrical energy} \]

  4. Exercise 4

    In a hydro power plant
    (a)
    Potential energy possessed by stored water is converted into electricity
    (b)
    Kinetic energy possessed by stored water is converted into potential energy
    (c)
    Electricity is extracted from water
    (d)
    Water is converted into steam to produce electricity

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    NCERT’s answer
    (a)
    (a) Water held at a height in the dam's reservoir possesses potential energy; released through penstocks, it turns the turbine coupled to the generator. \[PE_{\text{stored water}} \xrightarrow{\text{falls}} KE \xrightarrow{\text{turbine}} \text{mechanical energy} \xrightarrow{\text{generator}} \text{electrical energy} \]

  5. Exercise 5

    Which is the ultimate source of energy?
    (a)
    Water
    (b)
    Sun
    (c)
    Uranium
    (d)
    Fossil fuels

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    NCERT’s answer
    (b)
    (b) Sun — it drives winds and the water cycle; photosynthesis stores its energy in biomass and, over ages, in fossil fuels, so nearly all energy sources trace back to it.

  6. Exercise 6

    Which one of the following forms of energy leads to least environmental pollution in the process of its harnessing and utilisation?
    (a)
    Nuclear energy
    (b)
    Thermal energy
    (c)
    Solar energy
    (d)
    Geothermal energy

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    NCERT’s answer
    (c)
    (c) Solar energy — photovoltaic cells convert sunlight directly to electricity, with no fuel burning, no radioactive waste and no emissions, unlike nuclear, thermal or geothermal sources.

  7. Exercise 7

    Ocean thermal energy is due to
    (a)
    energy stored by waves in the ocean
    (b)
    temperature difference at different levels in the ocean
    (c)
    pressure difference at different levels in the ocean
    (d)
    tides arising out in the ocean

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    NCERT’s answer
    (b)
    (b) Ocean thermal energy comes from the temperature difference between warm surface water and cold deep water; this gradient drives the heat engine of an OTEC plant. \[\Delta T = T_{\text{surface}} - T_{\text{deep}} \geq 20^\circ\text{C} \Rightarrow \text{OTEC heat engine can run} \]

  8. Exercise 8

    The major problem in harnessing nuclear energy is how to
    (a)
    split nuclei?
    (b)
    sustain the reaction?
    (c)
    dispose off spent fuel safely?
    (d)
    convert nuclear energy into electrical energy?

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    NCERT’s answer
    (c)
    (c) Disposing of spent radioactive fuel safely — fission products stay intensely radioactive for thousands of years, and no method yet stores or neutralises this waste completely safely.

  9. Exercise 9

    Which part of the solar cooker is responsible for green house effect?
    (a)
    Coating with black colour inside the box
    (b)
    Mirror
    (c)
    Glass sheet
    (d)
    Outer cover of the solar cooker

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    NCERT’s answer
    (c)
    (c) Glass sheet. Sunlight enters as short-wavelength radiation and heats the blackened base; the base re-emits long-wavelength infrared that the glass will not transmit back out. \[\lambda_{short}\,(\text{in}) \Rightarrow \lambda_{long}\,(\text{trapped}) \Rightarrow T_{box}\uparrow \] This trapping of heat is the greenhouse effect.

  10. Exercise 10

    The main constituent of biogas is
    (a)
    methane
    (b)
    carbon dioxide
    (c)
    hydrogen
    (d)
    hydrogen sulphide

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    NCERT’s answer
    (a)
    (a) Methane. Anaerobic (oxygen-free) decomposition of biomass such as cattle dung and plant waste, inside a digester, yields biogas whose dominant combustible component is methane (roughly $\displaystyle 50$–$\displaystyle 70$%).