Answer
834 pm
Work Step by Step
Recall that the de Broglie wavelength $\lambda=\frac{h}{mv}$ where $h$ is the Planck's constant, $m$ is the mass and $v$ is the velocity.
Substituting values, we have
$ \lambda=\frac{6.626\times10^{-34}\,J\cdot s}{(1.67356\times10^{-27}\,kg)(475\,m/s)}$
$=8.34\times10^{-10}\,m=834\,pm$
