This question contains Statement -1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement - I:
Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
and
Statement - II
For heavy nuclei, binding energy per nucleon increases with increasing while for light nuclei it decrease with increasing Z.
Statement - I:
Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
and
Statement - II
For heavy nuclei, binding energy per nucleon increases with increasing while for light nuclei it decrease with increasing Z.
- (A)Statement - 1is false, Statement - 2 is true.
- (B)Statement - 1is true, Statement - 2 is true; Statement -2 is correct explanation for Statement-1.
- (C)Statement - 1is true, Statement - 2 is true; Statement - 2 is not a correct explanation for Statement-1.
- (D)Statement -1 is true, Statement -2 is False.✓ Correct
Answer: (D)
Solution
Energy is indeed released both when a heavy nucleus splits and when light nuclei fuse, because in each case the products move nearer the peak of the binding-energy-per-nucleon curve around iron, so the first statement is sound. The second statement, however, reverses the real trend: for heavy nuclei the binding energy per nucleon falls as the mass number grows, and it is precisely this fall that lets fission release energy, while for light nuclei it rises. Since the reason misdescribes how binding energy per nucleon varies, the first statement is true but the second is false.
JEE Main · 2008 · 27 Apr 2008 · Offline · Single correct option