Answer
$E = 8.2\times 10^{13}~J$
Work Step by Step
In part (a), we found that there are $2.56\times 10^{24}~atoms$
We can find the energy that is released:
$E = (2.56\times 10^{24})(200\times 10^6~eV)$
$E = 5.12\times 10^{32}~eV$
$E = (5.12\times 10^{32}~eV)(1.6\times 10^{-19}~J/eV)$
$E = 8.2\times 10^{13}~J$
