Write 'True' or 'False' and justify your answer:
$A$ spherical steel ball is melted to make eight new identical balls. Then,the radius of each new ball is $\frac{1}{8}$th the radius of the original ball.

How many cones with diameter $7\,cm$ and height $3\,cm$ can be produced by melting a metallic sphere with diameter $21\,cm$?

Total surface area of a cylinder with radius $7 \, cm$ and height $13 \, cm$ is $\ldots \ldots \ldots \ldots \, cm^{2}$.

Total surface area of a cone exceeds its curved surface area by $\ldots \ldots \ldots . . .$

The curved surface area of a cone is $85 \pi \, cm^{2}$. If its diameter is $10 \, cm$,its slant height is $\dots \dots \dots \dots \, cm$.

$A$ mason constructs a wall of dimensions $270 \,cm \times 300 \,cm \times 350 \,cm$ with bricks each of size $22.5 \,cm \times 11.25 \,cm \times 8.75 \,cm$. If $\frac{1}{8}$ of the total volume of the wall is occupied by mortar,find the number of bricks used to construct the wall.