Question

Assume that the nuclear binding energy per nucleon (B/A) versus mass number (A) is as shown in the figure. Use this plot to choose the correct choice(s) given below.

• A. Fusion of two nuclei with mass numbers lying in the range of $1<A<50$ will release energy
• B. Fusion of two nuclei with mass numbers lying in the range of $51<A<100$ will release energy
• C. Fission of a nucleus lying in the mass range of $100<A<200$ will release energy when broken into two equal fragments
• D. Fission of a nucleus lying in the mass range of $200<A<260$ will release energy when broken into two equal fragments

Answer 1

Answer: (B), (D)

The correct options are
B Fusion of two nuclei with mass numbers lying in the range of $51<A<100$ will release energy
D Fission of a nucleus lying in the mass range of $200<A<260$ will release energy when broken into two equal fragments

BE per nucleon is more for the products than the reactants.
As we see the plot, for A $>$ BE is less than that for the range $100<A<200$
Hence, fission will happen for the nuclei in the range $200$ to $260.$
Similarly the reactants for fusion will have mass number between 51 and 100 so that the product has mass number between $100$ and $200$.