A:- In the commercial process of extracting copper from low grade copper ores, iron scraps are preferred over zinc scraps as reducing agent

R:-SRP value of ${\mathrm{Fe}}^{2+}/\mathrm{Fe}<{\mathrm{Zn}}^{2+}/\mathrm{Zn}$.

${E^0}_{F{e}^{2+}/Fe}=-0.44V;{E^0}_{Z{n}^{2+}/Zn}=-0.76$

Reducing power $-Zn>Fe$

Although Zn has more reducing power than iron, iron is preferred over zinc as a reducing agent because Iron is cheaper as compared to Zinc.