The electrical potential energy between two point charges is given by:
[tex]V=k\frac{qQ}{r}[/tex]where:
k is the electrical constant
q, Q are the point charges
r is the distance between them
Protons have the same electric charge which is:
[tex]q=Q=+e=+1.6\cdot10^{-19}C[/tex]Lets plug the information in the formula above:
[tex]\begin{gathered} V=(9\cdot10^9)\cdot\frac{(1.6\cdot10^{-19})\cdot(1.6\cdot10^{-19})}{2.0\times10^{-5}} \\ V=11.52\cdot10^{9+(-38)-(-5)} \\ V=11.52\cdot10^{-24} \\ V\approx1.2\cdot10^{-23}V \end{gathered}[/tex]So our fina answer is:
[tex]V=1.2\cdot10^{-23}V[/tex]