This is fairly easy to prove, the diameter of the atom is of the order of [tex]10^{-15}[/tex]. Therefore an electron MUST be present in the volume of the atom. So, the maximum uncertainty that can be allowed is [tex]10^{-15}m[/tex]. Plug this into the equation and what do you get for the uncertainty in velocity?
HINT: Its greater than the speed of light, and that's just the UNCERTAINTY!
And the equation is [tex]dx\times dp>=\frac{h}{4\pi}[/tex].