A metallic sphere of radius 5 cm is melted to make a cone with base of the same radius. What is the height of the cone ?

Answer: Option D

Let the height of the cone be h cm
Then,
$$\begin{array}{rl}& \frac{4}{3}\pi \times {\left(5\right)}^3=\frac{1}{3}\pi \times {\left(5\right)}^2\times h\\ & \Rightarrow h=20cm\end{array}$$