Topic outline

    • Air

      Q1. Fill in the blanks.

                              i.        Troposphere layer is the most important layer of the atmosphere.

                             ii.        As we go up the layers of atmosphere, the pressure falls rapidly.

                            iii.        The trade winds, westerlies and easterlies are the permanent winds.

                            iv.        Cold air is denser and heavy.

                            v.        The air pressure is highest at sea level and decreases with height.

                           vi.        The upper most layer of the atmosphere is known as exosphere.


      Q2. True/False

                             i.        When air is heated, it expands, becomes lighter and goes up. True

                            ii.        High pressure is associated with clear and sunny skies. False

                           iii.        All living beings on this earth depend on the atmosphere for their survival. True

                           iv.        Carbon dioxide is the most plentiful gas in the air. False

                           v.        Green plants produce oxygen during photosynthesis. True

                          vi.        The air pressure is highest at sea level and decreased with height. True

      Q3. In which layer of the atmosphere do aeroplanes fly?

      Ans. Stratosphere


      Q4. Where do meteors burn up in the atmosphere?

      Ans. Mesosphere


      Q5. What is atmosphere?

      Ans. Our earth is surrounded by a huge blanket of air called atmosphere.


      Q6. What is the instrument that measures the amount of rainfall?

      Ans. Rain Gauge


      Q7. What is the instrument that measures the atmospheric pressure?

      Ans. Barometre


      Q8. What is the wind vane used for?

      Ans. Wind Vane shows the direction of the wind.

      Q9. Which layer of the atmosphere makes radio communication possible?

      Ans. Ionosphere


      Q10. Name the instrument which measures temperature.

      Ans. Thermometer


      Q11. What is the standard unit of measurement for temperature?

      Ans. The standard unit of measuring temperature is degree Celsius.


      Q12. Who invented the celsius scale of temperature?

      Ans. It was invented by Anders Celsius.


      Q13. What is the freezing and boiling point of water in celsius?

      Ans. On the Celsius scale the water freezes at 0°C and boils at 100°C.


      Q14. What is weather?

      Ans. Weather is hour-to-hour or day to day condition of the atmosphere.

      Q15. Which gas protects us from harmful sun rays?

      Ans. Ozone protects us from the harmful effect of the sun rays.


      Q16. Which layer of the atmosphere is free from clouds?

      Ans. Stratosphere layer is almost free from Clouds.


      Q17. What is rain?

      Ans. Precipitation that comes down to the earth in liquid form is called rain.


      Q18. What is loo?

      Ans. The hot and dry local wind of northern plane of India is called loo.


      Q19. Why do green plants use carbon dioxide?

      Ans. Green plants use carbon dioxide to make their food and release oxygen.


      Q20. What is the role of the ozone layer?

      Ans. Ozone layer protects us from the harmful effect of the sun rays.


      Q21. What is temperature?

      Ans. The degree of hotness and coldness of the air is known as temperature.


      Q22. What is insolation?

      Ans. Insolation is the incoming solar energy intercepted by the earth.


      Q23. Why is there no air pressure on moon?

      Ans. On the moon there is no air and hence no air pressure.


      Q24. What is humidity?

      Ans. Moisture in the air at any time is known as humidity.

    • Download to practice offline.