For a given cylinder,the diameter of the base is $7 \,cm$ and its height is $12 \,cm$. Find the curved surface area of a cylinder (in $cm^2$).

Write True or False and justify your answer.
$A$ right circular cylinder just encloses a sphere of radius $r$ as shown in the figure. The surface area of the sphere is equal to the curved surface area of the cylinder.

Curved surface area of a cylinder $= \ldots \ldots \ldots$

The diameter of a solid hemisphere is $21 \, cm$,then its volume is $\ldots \ldots \ldots \, cm^3$.

How many cubes of $1 \,cm$ edge can be cut from a wooden cuboid measuring $5 \,cm \times 4 \,cm \times 3 \,cm$? Find the ratio of the total surface area of the cuboid to the total surface area of all the cubes.

Find the curved surface area and the total surface area of a hemisphere with a radius of $17.5 \, cm$.