Question

A sphere is placed inside a right circular cylinder so as to touch the top, base and lateral surface of the cylinder. If the radius of the sphere is $r$, then the volume of the cylinder is

Answer 1

Radius of a sphere $=r$
Volume $=\frac{4}{3}\pi r^3$
$\therefore$ Radius of cylinder $\left(R\right)=r$
Height $\left(h\right)=2r$
$\therefore$ Volume $=\pi R^{2}H$
$=\pi r^2\times 2r=2\pi r^3$
Hence, option $\left(c\right)$ is correct.