Answer
An internal energy of $1029~J$ is produced per kilogram.
Work Step by Step
The increase in internal energy is equal to the initial gravitational potential energy of the water at a height of 105 meters:
$\Delta E = mgh$
$\Delta E = (1.0~kg)(9.80~m/s^2)(105~m)$
$\Delta E = 1029~J$
An internal energy of $1029~J$ is produced per kilogram.
