(c) repulsive and spin dependent
   (d) None of these
Ans: (a)
189. The nuclear force remains influential (effective) only upto :
   (a) 10-15m
   (b) 10-10m
   (c) 10-5m
   (d) 10-30m
Ans: (a)
190. The magnetic lines of force produced through a bar magnet: [NDA 2010]
   (a) cross inside the magnetic body
   (b) only cross across the neutral points of the magnet
   (c) only cross across the north pole and south pole
   (d) do not cross anywhere in the magnet
Ans: (d)
191. The nuclear force is a:
   (a) conservative force
   (b) non-conservative force
   (c) both of these
   (d) none of these
Ans: (a)
192. The phenomenon of natural radioactivity was invented by:
   (a) Henry Bacqurel
   (b) Rutherford
   (c) P. Curie
   (d) None of these
Ans: (a)
193. The phenomenon of artificial radioactivity was invented by:
   (a) Rutherford
   (b) Madam Curie
   (c) Newton
   (d) Dalton