A series of reactions in the Sun leads to the fusion of three helium nuclei $\left(_{2}^{4} \mathrm{He}\right)$ to form one carbon nucleus $\left(^{12}_{6} \mathrm{C}\right)$. (a) Determine the net energy released by the reactions. (b) What fraction of the total mass of the three helium nuclei is converted to energy?