The $TSA$ of a hemisphere with radius $10 \, cm$ is $\ldots \ldots \ldots \, cm^{2}$. (in $\pi$)

Find the number of metallic circular discs with $1.5\, cm$ base diameter and height $0.2\, cm$ that must be melted to form a right circular cylinder of height $10\, cm$ and diameter $4.5\, cm$.

For the science fair,a student prepared a model in the shape of a cylinder with radius $10 \,cm$ and height $40 \,cm$,closed at both ends by cones with slant height $26 \,cm$. How many litres of water can it contain?

The slant height of a cone with a hemispherical base is $5 \, cm$. If the total surface area of the article is $103.62 \, cm^2$,find its total height. $(\pi = 3.14)$ (in $cm$)

The Total Surface Area $(TSA)$ of a frustum of a cone is equal to $\ldots \ldots \ldots \ldots .$

$CSA$ of a cylindrical tank with diameter $2.1 \, m$ and height $5 \, m$ is $\ldots \ldots \ldots \ldots \, m^2$.