Physics

Problem

Average binding energy per nucleon for some nuclei is approximately:

^2_1\text{H}

1.1\,\text{MeV}

^3_1\text{H}

2.8\,\text{MeV}

^4_2\text{He}

7.0\,\text{MeV}

^{56}\text{Fe}

8.8\,\text{MeV}

. On this basis, which of the following reactions is most likely to release energy spontaneously? a)

^2_1\text{H}+ ^2_1\text{H}\;\rightarrow\; ^3_1\text{H}+ ^1_1\text{H}

^{56}\text{Fe}\;\rightarrow\; 2\times ^{28}_{14}\text{Si}

^2_1\text{H}+ ^3_1\text{H}\;\rightarrow\; ^4_2\text{He}+ ^1_0\text{n}

^4_2\text{He}+ ^4_2\text{He}\;\rightarrow\; ^8_4\text{Be}