CBSE  /  Class 9  /  Science  /  Natural Resources

  • 1. 
    Total Earth’s surface covered by water is

  • 75%
  • 60%
  • 85%
  • 50%

  • 2. 
    Biotic component of the biosphere is not constituted by

  • producers
  • consumers
  • decomposer
  • air

  • 3. 
    An increase in carbon dioxide content in the atmosphere would not cause

  • more heat to be retained by the environment
  • increase in photosynthesis in plants
  • global warming
  • abundance of desert plants

  • 4. 
    Oxygen is returned to the atmosphere mainly by

  • burning of fossil fuel
  • respiration
  • photosynthesis
  • fungi

  • 5. 
    Low visibility during cold weather is due to

  • formation of fossil fuel
  • unbumt carbon particles or hydrocarbons suspended in air
  • lack of adequate power supply
  • none of these

  • 6. 
    Growth of lichens on barren rocks is followed by the growth of

  • moss
  • ferns
  • gymnosperms
  • algae

  • 7. 
    Marked temperature changes in an aquatic environment can affect

  • breeding of animals
  • more growth of aquatic plants
  • process of digestion in animals
  • availability of nutrients.

  • 8. 
    Soil erosion can be prevented by

  • raising forests
  • deforestation
  • excessive use of fertiliser
  • overgrazing by animals

  • 9. 
    What happens when rain falls on soil without vegetational cover?

  • Rain water percolates in soil efficiently
  • Rain water causes loss of surface soil
  • Rain water leads to fertility of the soil
  • Rain water does not cause any change in soil

  • 10. 
    Oxygen is harmful for

  • ferns
  • nitrogen fixing bacteria
  • chara
  • mango tree
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