Three metallic solid cubes whose edges are $3 \, cm$,$4 \, cm$,and $5 \, cm$ are melted and formed into a single cube. Find the edge of the cube so formed (in $cm$).

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

The curved surface area of a cone with radius $12 \, cm$ and slant height $20 \, cm$ is ....... $\pi \, cm^2$.

Write 'True' or 'False' and justify your answer:
Two identical solid hemispheres of equal base radius $r \text{ cm}$ are joined together along their bases. The total surface area of the resulting solid is $6 \pi r^{2}$.

$A$ shuttlecock used for playing badminton has the shape of the combination of

$A$ container is in the form of a cylinder closed at one end by a hemisphere. The radius of the cylinder is $8.4 \,cm$ and the total height of the container is $52.8 \,cm$. How many litres of petrol can this container hold? (in $litres$)