The surface area of a sphere is $\ldots \ldots$

The $CSA$ (Curved Surface Area) of a $1-$ rupee coin is given by the formula $\ldots \ldots \ldots \ldots .$

$A$ cylinder is closed at both ends by $40 \, cm$ high cones. The radius of the cylinder is $30 \, cm$ and the total height of the article is $180 \, cm$. Find the total surface area of the article. $(\pi = 3.14)$ (in $cm^2$)

$A$ well with radius $2 \, m$ and depth $50 \, m$ is dug and the soil taken out is spread evenly on a circular plot with radius $40 \, m$. Find the increase in the level of the plot in $cm$.

The volume of a hemisphere is equal to:

The volume of a cylinder is $20 \pi \, cm^3$ and its height is $5 \, cm$. Then,the diameter of the cylinder is $\ldots \ldots \ldots \ldots \, cm$.