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

$A$ cube of side $4 \, cm$ contains a sphere touching its sides. Find the volume of the gap in between. (in $, cm^3$)

Find the curved surface area and the total surface area of a hemisphere with a radius of $2.1 \, m$.

Curved surface area of a cone $= \dots$

State whether the following statement is True or False and justify your answer: In a right circular cone,the height,radius,and slant height do not always form the sides of a right triangle.

The length and breadth of a cuboid are $30\, cm$ and $25\, cm$. If the total surface area of the cuboid is double the lateral surface area of the cuboid,find its height and volume.