A sphere of radius $r$ $\text{cm}$ is packed in a box of cubical shape.

What should be the minimum volume (in $\text{cm}^{3}$) of the box that can enclose the sphere?

1. $\frac{r^{3}}{8}$
2. $r^{3}$
3. $2r^{3}$
4. $8r^{3}$

Let the side of a cube be $a\;\text{cm}.$
$\Rightarrow \boxed{a = 2r}$
$\therefore$ The volume of a box of the cubical shape $= a^{3} = (2r)^{3} = 8r^{3} \;\text{cm}^{3}.$
Correct Answer $:\text{D}$