Li 7 fuses with& a proton& according to the nuclear reaction given...

The total mass of the initial particles

${m}_{i} = 1. 007825 + 7. 016004$

${m}_{i} = 8. 023829u$

and the total mass of final particles

${m}_{f} = 2 \times 4. 002603 = 8. 005206u$

Difference between the initial and final mass of particles

$= {m}_{i} - {m}_{f} = 8. 023829 - 8. 005206$

$= 0. 018623u$

The $Q$ value is given by

$Q = \left(∆ m\right)c^{2}$

$= 0. 018623 \times 931. 5 = 17. 35MeV$