To solve this problem, we apply the concepts related to the electrostatic force proposed by Coulomb's law. This force can be expressed as
![F = (kq_1q_2)/(d^2)](https://img.qammunity.org/2021/formulas/physics/college/q952qwmt0x7kqgc51mssjvkr3ulttfq0pp.png)
Here
k = Coulomb's constant
= Charge of each object
d = Distance between objects
We have that the charge are the same, and the distance and the force are
![d = 5*10^(-10) m](https://img.qammunity.org/2021/formulas/physics/college/266pg0m0ywgh3on42ww9zr2wpsx03edeqc.png)
![F = 9.20*10^(-10) N](https://img.qammunity.org/2021/formulas/physics/college/dr4xascd4zhw9d3houyt51wj5jjgb9e9ry.png)
Replacing we have,
![9.20*10^(-10) = (9.9*10^9*q^2)/(5*10^(-10))](https://img.qammunity.org/2021/formulas/physics/college/da7ht14updaqe9rtyk8apxk4nso9zejcu3.png)
Solving for q,
![q = 6.8165*10^(-15)C](https://img.qammunity.org/2021/formulas/physics/college/mpkn1v3bfycoz3t1zefe7cpp06qqk646bq.png)
Therefore the charge of each ion is
![6.8165*10^(-15)C](https://img.qammunity.org/2021/formulas/physics/college/jykibk5ailqoednu7cyci2p93fdtrhcvjg.png)