CBSE Class 12 Physics 2016 Delhi Set 1 Paper

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Question : 8
Total: 26
A nucleus with mass number A=240 and BE∕A=7.6‌MeV breaks into two fragments each of A=120 with BE∕A=8.5‌MeV . Calculate the released energy.
OR
Calculate the energy in fusion reaction :
‌12H+‌12H→‌23‌He+n , where BE of ‌12H=2.23‌MeV
and of ‌23‌He=7.73‌MeV .
Solution:  
Calculation of energy released
Binding energy of nucleus with mass number 240 ,
Ebn=240×7.6‌MeV
Binding energy of two fragments
‌=2×120×8.5‌MeV
‌ Energy released ‌=‌240(8.5−7.6)‌MeV
‌=240×0.9
‌=216‌MeV
OR
Calculation of Energy in the fusion Reaction
Total Binding energy of Initial System i.e.
‌12H+‌12H‌=(2.23+2.23)‌MeV
‌=4.46‌MeV
Binding energy of Final System i.e. ‌23‌He
=7.73‌MeV
Hence energy released
=7.73‌MeV−4.46‌MeV
=3.27‌MeV
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