What is the thermodynamic consideration in the choice of a reducing agent in metallurgy ?

Explanation

Highly electropositive elements are obtained by the electrolysis of their oxides, hydroxides or chlorides in fused state.
Extraction of less electropositive metals say `Cr,Mn,Cu,Ca,Ni` etc. can be done by heating their oxides with strong reducing agents, e.g. , `CO,CO + H_(2) ,Na,Al,Mg` etc.
The oxides of less electropositive metals like `Pb,Fe,Zn,Sb`, and `Cu` are reduced by strongly heating with coal or coke.