Helium nuclei combines to form an oxygen nucleus The energy released per nucleon of oxygen nucleus  is $\text{ [if }{m}_0=15.834 \mathrm{amu}\text{ and }{m}_{\mathrm{He}}=4.0026 \mathrm{amu}\text{ ] }$

The defect of mass,

$$\begin{gathered} \mathrm{m}=4\times {\mathrm{m}}_{\mathrm{He}}-{\mathrm{m}}_0 \\ \mathrm{m}=4\times 4.0026-15.834 \\ \mathrm{m}=0.1764\mathrm{amu} \\ \mathrm{m}=0.1764\times 1.66\times {10}^{-27} \mathrm{kg} \end{gathered}$$

The energy which is realsed,

$$\begin{gathered} \mathrm{E}={\mathrm{mC}}^2 \\ =0.1764\times 1.66\times {10}^{-27}\times {\left(3\times {10}^8\right)}^2 \\ =2.64\times {10}^{-11}{\mathrm{kgm}}^2{\mathrm{s}}^{-2} \\ =\frac{2.64\times {10}^{-11}}{1.602\times {10}^{-19}}\mathrm{eV} \\ =1.65\times {10}^8\mathrm{eV} \\ =165\mathrm{MeV} \end{gathered}$$