A uniform chain has a mass ' m ' and length l '. It is held on a frictionless table with…

Work done in pulling the hanging par of chain on table is equal to gain in potential energy,

$W=Mgh$

Mass of hanging part which is $\frac{1}{6}\mathrm{th}$of the total length, given that mass of chain is $m$is $\frac{m}{6}.$

Centre of mass is located at a distance $\frac{l}{12}$from the table.

$$\begin{gathered} \therefore W=\left(\frac{m}{6}\right)g\left(\frac{l}{12}\right) \\ \Rightarrow W=\frac{mgl}{72} \end{gathered}$$