(a) red
   (b) violet
   (c) green
   (d) yellow
Ans: (b)
186. Primary colours are
   (a) colours of the rainbow
   (b) colours in the spectrum of white light
   (c) colours which cannot be produced by mixing other colours
   (d) colours found in nature
Ans: (c)
187. In the visible spectrum which colour has the shortest wavelength?
   (a) Red
   (b) Blue
   (c) Yellow
   (d) Violet
Ans: (d)
188. When white light passes through a glass prism we get a spectrum on the
   other side of the prism. In the emergent beam the ray which is deviated least
   (a) the violet ray
   (b) the red ray
   (c) the green ray
   (d) the blue ray
Ans: (b)
189. Which part of the eye photographic camera?
   (a) Lens
   (b) Iris
   (c) Retina
   (d) Eyelid
Ans: (d)
190. The red colour of the setting sun is due to