S.R.P values of some electrodes are given below. 

$$\begin{gathered} {\mathrm{E}}_{{\mathrm{Mg}}^{+2}/\mathrm{Mg}}^{\mathrm{o}}=-2.37 \mathrm{V} ; \\ {\mathrm{E}}_{\frac{1}{2}{\mathrm{Cl}}_2/{\mathrm{Cl}}^{-}}^{\mathrm{o}}=+1.36 \mathrm{V} ; \\ {\mathrm{E}}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{\mathrm{o}}=+0.8 \mathrm{V} ; \\ {\mathrm{E}}_{{\mathrm{Zn}}^{+2}/\mathrm{Zn}}^{\mathrm{o}}=-0.76 \mathrm{V} ; \end{gathered}$$

From the above data, identify the best reducing agent

From the values of S.R.P

Tendency to undergo reduction …. ${\mathrm{Cl}}_2 > {\mathrm{Ag}}^{+} > {\mathrm{Zn}}^{+2}> {\mathrm{Mg}}^{+2}$

                      Oxidizing power …..  ${\mathrm{Cl}}_2 > {\mathrm{Ag}}^{+} > {\mathrm{Zn}}^{+2}> {\mathrm{Mg}}^{+2}$

                     Reducing power ….. $\mathrm{Mg} > \mathrm{Zn} > \mathrm{Ag} > {\mathrm{Cl}}^{-}$

Electrode with lower SRP value readily undergoes reduction