For a cell, the cell reaction is Mg(s)+Cu2+(aq)→Mg2+(aq)+Cu(s). If the S.R.P. values of Mg and Cu are −2.37 V and +0.34 V respectively, the EMF of the cell is:
Mg+2+2e→Mg; SRP=−2.37 V
Cu2++2e→Cu; SRP=0.34 V
∴ For reaction, Mg+Cu2+→Mg2++Cu
E0cell=E0Cu2+/Cu−E0Mg2+/Mg
E0cell=0.34−(−2.37)
E0cell=2.71 V
Option C is correct.