Answer
$5.494MeV$
Work Step by Step
We can find the required energy as follows:
First we find the mass of $H^1_1+H^2_1$
$m_i=1.007825u+2.014102u=3.021927u$
and the mass of $H^3_2$ is
$m_f=3.016029u$
$\Delta m=3.016029u-3.021927u=-0.005898u$
Now $E=\Delta mc^2$
We plug in the known values to obtain:
$E=0.005898u(\frac{931.5MeV/c^2}{1u})c^2$
$E=5.494MeV$
