Chapter 18: Pollution of Air and Water

1.Air is a mixture of various gases. One of the gases is 21% part of the air and is essential for the survival of human beings. This gas is
(a)nitrogen   (b)oxygen (c)ozone
  (d)argon
2.Which of the following is not a source of air pollution?
(a)automobile exhaust    (b)burning of firewood (c)windmill
  (d)power plant
3.Boojho wishes to contribute in reducing air pollution. Which vehicle should he use for going to school?
(a)car  (b)school bus         (c)autorickshaw
(d)scooter
4.Which of the following is not a way to conserve water?
(a)replace   (b)reduce  (c)reuse
  (d)recycle