Question

Binding energy per nucleon versus mass number curve for nuclei is shown in the figure. $W$ , $X$ , $Y$ and $Z$ are four nuclei indicated on the curve. The process that would release energy is

• A. $Y \rightarrow 2 Z$
• B. $W \rightarrow X + Z$
• C. $W \rightarrow 2 Y$
• D. $X \rightarrow Y + Z$

Answer 1

Answer: (C)

Energy is released in a process when total binding energy of the nucleus (= binding energy per nucleon $x$ number of nucleons) is increased or we can say when total binding energy of products is more than the reactants.
In the reaction $W \rightarrow 2 Y$
The binding energy of reactants $=120 \times 7.5=900\, MeV$
and binding energy of products $=2(60 \times 8.5)=1020 \,MeV$
and we can see $1020 \,MeV >900 \,MeV$.