Total surface area of a hemisphere with diameter $2 \, cm$ is $\ldots \ldots \ldots cm^{2}$.

The radius of a hemispherical dome of a temple is $21\, m$. Find the cost of painting its outer surface at the rate of ₹ $80/m^2$. (in ₹)

$CSA$ of a conical tank with height $3\,m$ and diameter $8\,m$ is $\ldots \ldots \ldots \ldots m^{2}$. $(\pi = 3.14)$

The radius of a sphere with surface area $1256\,cm^{2}$ is $\ldots \ldots \ldots cm$. $(\pi = 3.14)$

Write 'True' or 'False' and justify your answer:
An open metallic bucket is in the shape of a frustum of a cone,mounted on a hollow cylindrical base made of the same metallic sheet. The surface area of the metallic sheet used is equal to curved surface area of frustum of a cone + area of circular base + curved surface area of cylinder.

From a solid cylinder whose height is $2.4 \, cm$ and diameter is $1.4 \, cm$,a conical cavity of the same height and same diameter is hollowed out. Find the total surface area of the remaining solid to the nearest $cm^2$. [Take $\pi = \frac{22}{7}$]