Which of the following is the weakest reducing agent?

For the reactions $Ag^{+} (aq) + e^{-} \rightarrow Ag_{(s)}$ and $Sn^{2+} (aq) + 2e^{-} \rightarrow Sn_{(s)}$,the standard electrode potentials at $25^{\circ}C$ are $0.80 \ V$ and $-0.14 \ V$ respectively. What is the standard $emf$ of the cell $Sn_{(s)} | Sn^{2+}_{(aq)} (1 \ M) || Ag^{+}_{(aq)} (1 \ M) | Ag_{(s)}$ in $volts$?

Can the absolute electrode potential of an electrode be measured?

At ${25 \, ^\circ C}$,the standard reduction potentials for $Li^+/Li$,$Ba^{2+}/Ba$,$Na^+/Na$,and $Mg^{2+}/Mg$ are $-3.05 \, V$,$-2.73 \, V$,$-2.71 \, V$,and $-2.36 \, V$ respectively. Which of the following is the strongest oxidizing agent?

Electrode potentials of five elements $A, B, C, D$ and $E$ are respectively $-1.36 \ V, -0.32 \ V, 0 \ V, -1.26 \ V$ and $-0.42 \ V$. The reactivity order of these elements is:

Zinc can be coated on iron to produce galvanized iron,but the reverse is not possible. This is because: