A filled bed consisting of solid materials with a density of $2000k\frac{g}{m^3}$ covers a volume of $0\mathrm{.}6m$ depth in a cylindrical container with an inner diameter of $0\mathrm{.}1m.$ The mass of the solids in the bed is $5kg,$ and the surface$-$to$-$volume average diameter of the particles is $300m.$ Water $($density $1000k\frac{g}{m^3}$ and viscosity $0\mathrm{.}001$ Pa$.$s$)$ flows upward through the bed.

a$)$ The void fraction $()$ of the filled bed,

b$)$ Calculate the fluid velocity when a pressure drop of $4130Pa$ occurs across the bed. $5)$ A hydrocarbon