Answer
See explanation.
Work Step by Step
Compare the mass of the original C nucleus to the total mass of the beta particle and nitrogen nucleus.
The $\beta^-$ particle has a charge of -1 and a mass number of 0, so the new nucleus will have a mass number of 14, and an atomic number of 6 – (-1) = 7. It is nitrogen, $^{14}_{7}N$.
Calculate the mass defect, 14.003242u-14.003074u=0.000168u. The number of electrons stays the same.
Recall that 1 u = 931.5 MeV.
This mass defect corresponds to an energy release of 0.156 MeV.
