Force acts on charge$5\mu C$ due to charge$10\mu C$ is${\text{F}}_{\text{1}}$ and force acts on charge$10\mu C$ due to charge$5\mu C$ is ${\text{F}}_{\text{2}}$ for same separation. Ratio of ${\text{F}}_{\text{1}}$ and ${\text{F}}_{\text{2}}$ is

${\text{q}}_2=10\mu \text{C}=10\times {10}^{-6}\text{C}$

${\text{r}}_{12}=\text{r}$

${\text{F}}_1=\frac{1}{4\pi {\epsilon }_0}\times \frac{5\times {10}^{-6}\times 10\times {10}^{-6}}{{\text{r}}^2}$

${\text{F}}_2=\frac{1}{4\pi {\epsilon }_0}\times \frac{10\times {10}^{-6}\times 5\times {10}^{-6}}{{\text{r}}^2}$

$\frac{{\text{F}}_{\text{1}}}{{\text{F}}_{\text{2}}}=\frac{\frac{1}{4\pi {\epsilon }_0}\times \cancel{\frac{5\times {10}^{-6}\times 10\times {10}^{-6}}{{\text{r}}^2}}}{\frac{1}{4\pi {\epsilon }_0}\times \cancel{\frac{10\times {10}^{-6}\times 5\times {10}^{-6}}{{\text{r}}^2}}}=\frac{1}{1}=1:1$

i.e Separation is same : same static force [so not change of static force between two charges ] [static force depends on the separation between two charges]