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 $cm^2$?

Metal spheres,each of radius $2 \, cm$,are packed into a rectangular box of internal dimensions $16 \, cm \times 8 \, cm \times 8 \, cm$. When $16$ spheres are packed,the box is filled with preservative liquid. Find the volume of this liquid. Give your answer to the nearest integer. [Use $\pi = 3.14$] (in $cm^3$)

The ratio of the radius and slant height of a cone is $3:5$ and its curved surface area is $423.9 \, cm^2$. Find its volume. $(\pi = 3.14)$ (in $cm^3$)

State whether the following statement is true or false:
The area of the base of a cylinder is $154 \, cm^{2}$ and its height is $20 \, cm$, then its volume is $3080 \, cm^{3}$.

Find the surface area of a sphere of diameter $3.5\,m$ (in $m^2$).

Find the volume of a sphere with radius $2.1 \, m$ (in $m^{3}$).