question_answer

                Nuclear fission can be explained by:                                                                                                       

A)                 proton-proton cycle                                                      

B)                 liquid drop model of nucleus

C)                 independent of nuclear particle model 

D)                 nuclear shell model

Correct Answer: B

Solution :

                Neil Bohr and J.A. Wheeler explained the nuclear fission on the basis of liquid drop model of the nucleus. The \[_{92}{{U}^{235}}\] nucleus behaves like a liquid drop and owing to surface tension is perfectly spherical in shape. When the neutron strikes the nucleus, some energy called the excitation energy is imparted to the nucleus. The phenomenon of surface tension tries to keep the nucleus spherical in shape, whereas the excitation energy tries to deform it. Due to the struggle between the surface tension and the excitation energy, the oscillations are set up inside the compound nucleus. As a result the nucleus gets deformed from spherical shape to ellipsoidal and then to a dumb bell as shown, till the Coulomb's repulsive force between protons succeeds in tearing the two bells apart.