The electrostatic potential of a uniformly charged thin spherical shell of charge Q and radius R at a distance r from the centre is

$\frac{Q}{4\pi {\epsilon }_{0}r}$ for points outside and  $\frac{\mathrm{Q}}{4\pi {\epsilon }_0\mathrm{R}}$ for points inside the shell

zero for points outside and $\frac{Q}{4\pi {\epsilon }_{0}r}$ for points inside the shell

$\frac{\mathrm{Q}}{4\pi {\epsilon }_0\mathrm{r}}$ for both points inside and outside the shell

zero for both points inside and outside the shell