Find $(i)$ the curved surface area and $(ii)$ the total surface area of a hemisphere of radius $21\, cm$.

$A$ sphere and a right circular cylinder of the same radius have equal volumes. By what percentage does the diameter of the cylinder exceed its height?

$A$ godown measures $60 \,m \times 25 \,m \times 15 \,m$. Find the maximum number of wooden crates each measuring $1.5 \,m \times 1.25 \,m \times 0.5 \,m$ that can be stored in the godown.

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

If the edge of a cube is $7\, cm$,find its total surface area in $cm^2$.

$A$ cubical box has each edge $10\, cm$ and another cuboidal box is $12.5\, cm$ long, $10\, cm$ wide and $8\, cm$ high. Which box has the smaller total surface area and by how much (in $ cm^2$)?