Water boils at a lower temperature at high altitudes, because

  1. the air pressure is less
  2. outside temperature is less
  3. less latent heat is less
  4. None of the above
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When pure water boils vigorously, the bubbles that rise to the surface are composed primarily of

  1. air
  2. hydrogen
  3. hydrogen and oxygen
  4. water vapour
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Potable water is the water which is

  1. obtained from a river
  2. obtained from a lake
  3. pure and fit for drinking
  4. used only for washing clothes
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The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining proper hygiene per person per day is a minimum of

  1. 5 litres
  2. 15 litres
  3. 30 litres
  4. 50 litres
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On which of the following day is World Water Day observed?

  1. 22 March
  2. 14 November
  3. 2 October
  4. 21 December
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Transpiration is a process in which plants

  1. receive water from soil.
  2. absorb water vapour from air.
  3. prepare food from water.
  4. release water vapour.
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