Two identical cubes each of volume $64 \, cm^{3}$ are joined together end to end. What is the surface area of the resulting cuboid? (in $cm^{2}$)

$A$ cylindrical tank is closed at both the ends by cones of height $12 \, cm$. The diameter of the cylindrical part is $14 \, cm$ and its height is $20 \, cm$. Find the volume of this tank (in $cm^3$).

$A$ cylindrical bucket of height $32 \,cm$ and base radius $18 \,cm$ is filled with sand. This bucket is emptied on the ground and a conical heap of sand is formed. If the height of the conical heap is $24 \,cm$,find the radius and slant height of the heap.

$A$ right circular cylinder of radius $r \, cm$ and height $h \, cm$ (where $h > 2r$) just encloses a sphere. What is the diameter of the sphere (in $cm$)?

$A$ metallic sphere with radius $42\, cm$ is melted to cast $8000$ identical balls. Find the radius of these balls (in $cm$).

The volume of the largest right circular cone that can be cut out from a cube of edge $4.2 \,cm$ is (in $cm^3$)