The radius of a sphere is $2r$,then its volume will be

Write True or False and justify your answer: The volume of a sphere is equal to two-thirds of the volume of a cylinder whose height and diameter are equal to the diameter of the sphere.

$A$ hemispherical bowl has a radius of $3.5\, cm$. What would be the volume of water it would contain (in $, cm^{3}$)?

How many litres of milk can a hemispherical bowl of diameter $10.5\, cm$ hold (in $, l$)?

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

$A$ shot-put is a metallic sphere of radius $4.9 \, cm$. If the density of the metal is $7.8 \, g/cm^3$,find the mass of the shot-put. (in $, kg$)