Answer
$\frac{\Delta K}{K}=1.0 .$
Work Step by Step
The mass of a neutron is $1.0 \mathrm{u}$ and the mass of a hydrogen atom is also $1.0 \mathrm{u}$. Thus,
$
\frac{\Delta K}{K}=\frac{4(1.0 \mathrm{u})(1.0 \mathrm{u})}{(1.0 \mathrm{u}+1.0 \mathrm{u})^2}\\=1.0 .
$
