203. The nuclear reactor is an example of : [RRB ASM/GG 2004]
   (a) controlled fission
   (b) uncontrolled fission
   (c) uncontrolled fusion
   (d) none of these
Ans: (a)
204. The image of an object kept on the centre of curvature of a concave
   mirror is formed-[NDA 2010]
   (a) at main focus
   (b) between main focus and centre of curvature
   (c) between pole and infinity
   (d) none of these
Ans: (c)
205. Through a beaker containing water a coin kept inside it seems to be
   upwardly lifted because of-[NDA 2010]
   (a) reflection of light
   (b) refraction of light
   (c) total internal reflection of light
   (d) interference of light
Ans: (b)
206. Cobalt-60 is usually utilised is radiotherapy because of emission of : [IAS
   (Pre) 1999]
   (a) alpha rays
   (b) beta rays
   (c) gamma rays
   (d) X-rays
Ans: (d)
207. The fuel used in the breeder reactor is :
   (a) thorium
   (b) uranium
   (c) deuterium
   (d) uranium-235