In a cylinder,if the radius is doubled and the height is halved,the curved surface area will be:

Rain water which falls on a flat rectangular surface of length $6\, m$ and breadth $4\, m$ is transferred into a cylindrical vessel of internal radius $20\, cm$. What will be the height of water in the cylindrical vessel if the rainfall is $1\, cm$? Give your answer to the nearest integer. (Take $\pi = 3.14$) (in $cm$)

Find the curved surface area and the total surface area of a hemisphere with a diameter of $14 \, cm$.

The radius of a cone is $15 \, cm$ and its slant height is $25 \, cm$. Find the curved surface area and the total surface area of the cone. $(\pi = 3.14)$

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.

Find the surface area and volume of a sphere of diameter $28 \, cm$.