Answer:
The answer is [tex] -9.239 \times 10^{-8}\ N = [/tex]
Explanation:
The definition of electric force between two puntual charges is
[tex]F_e = \frac{K q_1 q_2}{d^2}[/tex]
where
[tex]K = 9 \times 10^9\ Nm^2/C^2[/tex].
In this case,
[tex]q_1 = e = 1.602\times 10^{-19}\ C[/tex],
[tex]q_2 = -e = -1.602\times 10^{-19}\ C[/tex]
and
[tex]d = 5 \times 10^{-11}\ m[/tex].
So the force is
[tex]F_e = -9.239 \times 10^{-8}\ N [/tex]
where the negative sign implies force of attraction.