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

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

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

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

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.

$A$ school provides milk to the students daily in cylindrical glasses of diameter $7\, cm$. If the glass is filled with milk up to a height of $12\, cm$, find how many litres of milk is needed to serve $1600$ students. (in $0.2$)