Answer
$K_{max} = 0.782~MeV$
Work Step by Step
Note that the energy equivalent of $1 u$ is $931.494~MeV$
We can find the maximum possible value of the kinetic energy:
$K_{max} = (840\times 10^{-6})(931.494~MeV)$
$K_{max} = 0.782~MeV$
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