If the edge of a cube is $12 \, cm$,find its volume (in $cm^3$).

$A$ right triangle with sides $6 \, cm, 8 \, cm$ and $10 \, cm$ is revolved about the side $8 \, cm$. Find the volume and curved surface area of the cone so formed. $(\pi = 3.14)$

The diameter of a solid hemisphere is $42\, cm.$ Find the curved surface area of a hemisphere (in $cm^2$).

There are two boxes of metal sheet. The length,width,and height of a cuboidal box are $30 \, cm$,$25 \, cm$,and $20 \, cm$ respectively. $A$ cubical box has each edge of $25 \, cm$. Find out which box requires more metal sheet and by how many $cm^2$?

The diameter of a solid hemisphere is $7 \, cm$. Find its curved surface area and total surface area (in $cm^2$).

Two cubes each of $8 \, cm$ edge are joined end to end. Find the total surface area of the cuboid so formed (in $cm^{2}$).