Write two characteristic properties of nuclear force. How does one explain the release of energy in the processes of nuclear fusion and nuclear fission ?                                        (3 marks)

(a)  (i) Strong force

      (ii) short range

      (iii) charge independence

      (iv) spin dependence 

              [Note : Any two characteristic properties]                                  12+12 marks   


(b)    Explanation :

        In the case of fussion of two very light nuclei forming a heavier nucleus, the B.E./A of heavier

        nucleus is more than that of light nuclei. The difference causing the release of energy. (1 marks)

         In fission, a heavy nucleus has lower binding enegry compared to that of nuclei with lower 

         mass number. When a nucleus with A=240 breaks into two of A=120 each, nuclei get more

         tightly bound, causing the release of energy.                                         (1 marks)

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