Question

if charge density is ar^2+br then is it cyldrical surface?

Answer 1

No

Answer 2

The given charge density $\rho = ar^2 + br$ is a volume charge density, meaning charge is distributed throughout a volume. A cylindrical surface, by definition, is a two-dimensional object where charge would be distributed as a surface charge density ($\sigma$). Therefore, a volume charge density cannot be a cylindrical surface.