Twelve solid spheres of the same size are made by melting a solid metallic cylinder of base diameter $2 \, cm$ and height $16 \, cm$. The diameter of each sphere is (in $cm$):

Write 'True' or 'False' and justify your answer:
The curved surface area of a frustum of a cone is $\pi l(r_{1}+r_{2})$,where $l = \sqrt{h^{2}+(r_{1}+r_{2})^{2}}$,$r_{1}$ and $r_{2}$ are the radii of the two ends of the frustum,and $h$ is the vertical height.

The base of a cone with radius $0.6 \ m$ and height $1.6 \ m$ is hemispherical. Find the volume of this combined solid in $m^{3}$.

$A$ hemispherical bowl of internal radius $9 \,cm$ is full of liquid. The liquid is to be filled into cylindrical shaped bottles each of radius $1.5 \,cm$ and height $4 \,cm$. How many bottles are needed to empty the bowl?

$A$ cylinder with radius $21 \, cm$ and height $18 \, cm$ is closed at both the ends by hemispheres. Find the surface area of this article. $(\pi = \frac{22}{7})$ (in $cm^2$)

How many balls with diameter $0.5\, cm$ can be produced by melting a metallic cylinder with radius $2\, cm$ and height $8\, cm$?