Dear Student,
There is a uniformly charged non conducting solid sphere made up of material of dielectric constant one. If electric potential at infinity be zero, then the potential at its surface is V.
For non conducting sphere, the potential at its surface is equal to potential at center.
And here is given that potential at its surface is zero then at center potential is also zero.
Cheers!!
Regards,
Vikas (B. Tech. 4th year
Thapar University)