Answer
$F=2.9\times10^{-9}N$
Work Step by Step
Electrostatic force can be calculated from the following equation:
$F=\frac{Kq_1q_2}{r^2}$
We know that in the case of positive and negative ions (i.e electrons and protons) $q_1=q_2=q$, where $q=1.6\times10^{-19}C$
Thus $F=\frac{Kq^2}{r^2}$
Plugging in the known values, we obtain:
$F=\frac{9\times10^9(1.6\times10^{-19})^2}{(2.82\times10^{-10})^2}$
$F=2.9\times10^{-9}N$
