$A$ cylinder is closed at both ends by hemispheres. The radius of the cylinder is $21 \, cm$ and the total height of the article is $92 \, cm$. Find the total surface area of the article (in $cm^2$).

The $TSA$ of a hemisphere with radius $10 \, cm$ is $\ldots \ldots \ldots \, cm^{2}$. (in $\pi$)

Total surface area of a closed cube $= \dots$

For a given frustum of a cone,the circumference of the base is $48 \, cm$ and the circumference of the top is $36 \, cm$. If its height is $11 \, cm$,find its volume (in $cm^3$).

The volume of a sphere is $4.5 \pi \, cm^3$. Then,its diameter is $\ldots \ldots \ldots \ldots cm$.

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.