156. Warm air will hold more water vapour than cold air because
   (a) it is lighter
   (b) it has more water vapour in it
   (c) its molecules are close together
   (d) its molecules are far apart
Ans: (d)
157. Why is it cool near an open pond on a hot summer day?
   (a) Evaporation at the surface causes cooling
   (b) The heat obsorbed at the surface is passed on to the bottom
   (c) Because of impurity in the water
   (d) Because of convection currents set up inside water
Ans: (a)
158. The radiator in a car serves to
   (a) cool the engine
   (b) heat up the engine
   (c) start the car
   (d) moderate the speed
Ans: (a)
159. The speed at which light travels in vacuum is
   (a) 3 x 107 ms-1
   (b) 5 x 108 ms-1
   (c) 3 x 104 kms-1
   (d) 3 x 108 ms-1
Ans: (d)
160. Light from the sun reaches the earth in
   (a) 2 minutes
   (b) 4 minutes
   (c) 12 minutes
   (d) 8 minutes
Ans: (d)
161. The shadow below a tree has bright spots in it because
   (a) light comes through circular gaps between the leaves