Correct option (b) 3.6 J
Explanation:
Mass per unit length = M/L = 4/2 = 2 kg/m
The mass of 0.6 m of chain = 0.6 x 2 = 1 .2 kg
The height of centre of mass of hanging part
h = 0.6 + 0/2 = 0.3 m
Hence, work done in pulling the chain on the table = Work done against gravity force
i.e, W = mgh
= 1.2 x 10 x 0.3 = 3.6 J