The edge of a cube is $35\, cm$. Find the total surface area of the cube (in $cm^2$).

$A$ cuboidal water tank is $2\, m$ long,$1\, m$ wide,and $80\, cm$ deep (height). Its remaining five surfaces,excluding the base,are covered with square tiles of size $20\, cm \times 20\, cm$. Find the number of tiles required.

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

The radius of the base of a cone is $7 \, cm$ and its height is $30 \, cm$. Find the volume of a cone (in $cm^3$).

Find the volume of a sphere of radius $2.1 \, cm$. (in $cm^3$)

Each of the radius of a cylinder and a sphere is $9 \, cm$. If the volumes of these solids are equal,find the height of a cylinder (in $cm$).