The $TSA$ (Total Surface Area) of a $5$-rupee coin is given by the formula $\ldots \ldots \ldots . .$

The radius and height of a cone are $5\,cm$ and $12\,cm$ respectively. Then,the ratio of its $CSA$ and area of base is $\ldots \ldots \ldots \ldots$

$1 \text{ litre} = \dots \text{ cm}^3$

The $CSA$ of a cone with radius $4 \, cm$ and slant height $6 \, cm$ is $\ldots \ldots \ldots \ldots cm^{2}$. (in $\pi$)

The base of a cone with radius $15 \, cm$ and slant height $25 \, cm$ is hemispherical. Find the volume of this solid. $(\pi = 3.14)$ (in $cm^3$)

Write 'True' or 'False' and justify your answer:
The curved surface area of a frustum of a cone is $\pi l(r_{1}+r_{2})$,where $l = \sqrt{h^{2}+(r_{1}+r_{2})^{2}}$,$r_{1}$ and $r_{2}$ are the radii of the two ends of the frustum,and $h$ is the vertical height.