What is the linear density of the chain?  
Note that you are not lifting the whole length of the rope!  
Express the answer in terms of the total mass M of the rope, 
the total length L of the rope, and the height H 
to which the end of the rope is raised; 
do NOT replace M, L, and H by their numerical values 
while you are solving the problem, but only after you 
obtained the answer in terms of M, L, and H.