(b) velocity
   (c) energy widely used in nuclear physics
   (d) number of electrons
Ans: (c)
349. Photoelectric cell is a device which converts
   (a) light energy into electrical energy
   (b) electrical energy into light energy
   (c) magnetic energy into electrical energy
   (d) electrical energy into mechanical energy
Ans: (a)
350. Changing of one element into another element is known as
   (a) transmutation
   (b) fission
   (c) fusion
   (d) radioactivity
Ans: (a)
351. Enriched uranium means
   (a) Uranium that is very pure
   (b) Uranium in which the concentration of the isotope U-238 is more than in
       the naturally occuring uranium
   (c) Uranium in which the concentration of the isotope U-235 is more than in
       the naturally occuring uranium
   (d) None of the above
Ans: (c)
352. Photocells are used
   (a) in burglar alarms
   (b) in automotive devices for light switches
   (c) television cameras
   (d) All the above
Ans: (d)
353. Nuclear fission process means
   (a) absorption of a neutron by a nucleus
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