The capacity of a cylindrical tank with radius $1.4 \, m$ and height $4 \, m$ is $\ldots \ldots \ldots$ litres.

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 ₹)

The base of a cone with radius $21 \, cm$ and height $20 \, cm$ is hemispherical. Find its curved surface area and volume.

Twelve solid spheres of the same size are made by melting a solid metallic cylinder of base diameter $2 \, cm$ and height $16 \, cm$. The diameter of each sphere is (in $cm$):

$A$ cylinder is closed at both ends by $12 \, cm$ high cones. The radius of the cylinder is $5 \, cm$ and the total height of the article is $41 \, cm$. Find the total surface area of the article. $(\pi = 3.14)$ (in $cm^2$)

The slant height of a cone with radius $6 \, cm$ and height $8 \, cm$ is $\ldots \ldots \ldots \ldots cm$.