The radius of the internal and external surfaces of a hollow spherical shell are 3 cm and 5 cm respectively.

Given that,

Internal radius of the sphere = 3 cm = r1

External radius of the sphere = 5 cm = r2

Height of the cylinder = 8/3cm = h

Volume of the spherical shell = Volume of cylinder

$\frac{4}{3} \pi\left(r_{2}^{3}-r_{1}^{3}\right)=\pi r_{3}^{2} h$

$\frac{4}{3}\left(5^{3}-3^{3}\right)=\frac{8}{3} r_{3}^{2}$

$r_{3}^{2}=\frac{4 \times 98 \times 3}{3 \times 8}$

$r_{3}=\sqrt{49}$

r3 = 7cm

Therefore diameter of the cylinder = 2(radius) = 14 cm