A small uncharged conducting sphere is placed in contact with an identical sphere but having 4 × 10^-8 C charge and then removed to a distance such…

A small uncharged conducting sphere is placed in contact with an identical sphere but having $\displaystyle 4 \times 10^{-8} \mathrm{C}$ charge and then removed to a distance such that the force of repulsion between them is $\displaystyle 9 \times 10^{-3} \mathrm{~N}$. The distance between them is (Take $\displaystyle \frac{1}{4 \pi \epsilon_{\mathrm{o}}}$ as $\displaystyle 9 \times 10^9$ in SI units)